A dog guards the padlocked entrance.

Reyes, a retired junk-shop owner, has a dozen fighting cocks and 16 birds that are not yet fully grown or ready to fight.

"I breed them right from the eggs," he says, proudly. It usually takes about nine months after hatching for the roosters to be ready to fight, and even then, only some have what it takes.

"You have to be harsh - if a cock don't want to fight, you need to kill it and eat it."

With that, Reyes releases two of his prized cocks. The birds launch at each other in a frenzy of feathers and pecking. The cocks have gloves over their talons, to prevent serious injuries, but the violence is palpable, and feathers fly as the birds refuse to submit.

A smiling Reyes pulls the two struggling birds apart and, with a tender touch, places each of them gently back in their cages.

"A good cock fights best when it is three or four years old," says Reyes. "They might win dozens of fights."

"This cock is blind," he says, pointing to one of the two who have just fought, "but it has still won twice when blind. I'm proud of it."

Banned in much of the world, in the Philippines cockfighting is not only legal, it is practically a national sport. According to the National Federation of Gamefowl Breeders, the umbrella organisation for the Philippines' cockfighting associations, there are more than 2,000 legal cockpits nationwide, along with thousands of unlicensed operations and fights that happen in makeshift cockpits at the sides of roads.

Millions of dollars change hands daily in gambling while hundreds of thousands of Filipinos are said to be employed in and around the sport, whether breeding, working in the cockpits or selling cages, fighting blades, chicken feed and medicine.

Filipino politicians support the tradition, which dates back hundreds of years, and the occasional mutters about banning the practice due to cruelty to animals fall mostly on deaf ears.

"Try abolishing cockfights in the country, the next day we will have another president," Roliveth "Boyet" Cortes, a businessman-turned-politician campaigning for a position as a regional governor, told the media in November.

On fight days - particularly Sundays and religious holidays - cockpits around the country fill up with people, mostly men but also women and children. Driving through small towns you can often see illicit cockpits operating on dusty, crowded streets.

Less than a kilometre from where Reyes lives stands La Loma, supposedly the oldest cockpit in the Philippines. Hundreds of dusty motorbikes cram into the space in front of the arena; paint peels off the outside walls. Just inside the entrance a sign reads, "Leave your firearms at the gate".

While tourists flock to Libertad, a cleaner, more central arena, La Loma, opened in 1902, is a local affair. The cockpit has little in the way of creature comforts; instead, there are hard plastic seats, rusty metal railings, trails of blood on the floor and low-hanging strip lighting.

me accompany him to the cockpit as he prepares two of his cocks to fight. Sliding me through the gate with a nod to the security guard, he leads me into the bowels of La Loma.

It is a seedy and intimidating environment to step into, but it is worth bearing in mind that most people are here to watch and appreciate what they consider a contest of strength, bravery and endurance. And perhaps win a few pesos.

"It's like boxing," national hero Manny Pacquiao, a former world super-bantamweight-boxing champion, told magazine in November 2011. Pacquiao, who had his own farm with more than 1,000 fighting cocks before announcing he was giving up the practice early last year, added: "The rooster has to be in shape. He has to train for the fight and he has to have so much fight in his heart."

The scene inside La Loma is chaotic. Row after row of concrete seats are crammed with hundreds of spectators, noisily betting on the action. All eyes are focused on the small blur of movement in the centre of the arena. Large fans blow warm air into the crowds of men, doing little to dispel the sticky heat.

Fights come thick and fast, some lasting several minutes, others just 10 seconds. When a fight ends, the dirt floor is swept clear of feathers, the trainers and their birds are hustled out and a new pair of cocks brought forward. Many of the trainers belong to teams, and their names or logos are shown on boards, while their records are known by hard-core fans and gamblers.

Before each fight, opposing trainers approach each other and hold their birds inches apart, to allow them to peck one another and arouse their territorial instincts. After that, it is a matter of letting the cocks loose and hoping for the best.

It is rarely pretty, and with sharp three-inch blades attached to their left legs, most birds sustain serious injuries. Sometimes neither leaves the cockpit alive.

VIP boxes ring the upper reaches of the arena but the best seats in the cockpit are those up against the glass that divides the small fighting pit from the crowd. From here, trainers and gamblers can size up the combatants, assessing their height, age and demeanour. Several of the men in these seats are nervously smoking cigarettes as they make their bets. Butts litter the ground.

"We are serious about our gambling," says Choy Dizon, a 50-year-old businessman who cannot take his eyes off the action. Every now and then he raises his hands and, with complicated gestures, places a bet with one of the bookies. Each is of about HK$100.

"I used to come every day but I lost too much. Now I just come on special occasions," he says.

La Loma is packed "almost every day. Sometimes it goes on until 5am - when all the day's fights are finally done. By then it is almost time to start the new [fighting] day," a regular inside the arena says.

While cockfighting is considered a great leveller - an arena in which ordinary Filipinos can mingle with the wealthy, politicians and celebrities - most of those who frequent La Loma are from the city's underclass: drivers and manual labourers, restaurant workers and gambling addicts.

Thousands have for decades called a nearby cemetery home, living literally among the dead.

Some of those who fail to pay their debts at La Loma hide out in the cemetery, hoping to escape punishment.

"The No1 rule here is pay your debts," says George Guballa, a 33-year-old who came to La Loma as a child, with his father. "My dad used to tell me of people who would be beaten outside if they tried to run. One of father's friends lives in the cemetery. He can't come around here as he owes bad men serious money."

trainers gather in the harsh afternoon sun, waiting their turn to take in their roosters. Groups of older men watch over their cocks. Some have cages but others simply cradle their birds in their arms, waiting for their turn to step into the ring.

Standing on the stained concrete are a couple of buckets filled with bloody water and the carcasses of birds who have fought for the last time. They will be taken home and eaten; if your cock is killed in the ring, your opponent is given the carcass.

Many of the fighting birds are kept in shaded and padlocked rooms at the back while they wait their turn to fight. This is to keep them cool and relaxed, but also to protect them.

"People cheat," Reyes says. "They put poison in the cock's food when you're not looking, or in the feathers of their own bird so that when the fight is underway your bird might peck some of the poison."

It has also been known for rival trainers to break into the locked storerooms, so guards are posted.

The money involved in cockfighting in the Philippines is significant. The government is said to earn billions of pesos a year by taxing licensed cockpits, and for trainers the prize money on offer can be huge.

Last January, the semi-annual World Slasher Cup, held at a huge sports stadium in downtown Manila, drew 300 participants with its record first prize of 15 million pesos (HK$2.8 million). Thousands of cockfighting fans crammed into the 16,000-seater stadium, which in recent years has hosted performances by Avril Lavigne, Kylie Minogue, Kelly Clarkson and Taylor Swift.

Some trainers spend thousands of dollars on birds, importing them from overseas; Pacquiao was estimated to have fighting roosters worth about US$700,000 in total.

"I buy cocks from West Virginia, Texas and Canada," says trainer Robert Lee. Dressed in a bright yellow shirt and standing protectively beside three wooden cages, the 40-year-old, explains that birds from North America are bigger and stronger, but more expensive: "From Texas, it might cost me US$25,000 for 10 birds."

Lee is half-Chinese, with a father from Macau - another place, he points out, that loves to gamble. He's been raising fighting cocks full-time for 25 years.

"It is my business. I have 1,000 cocks, young and old, on a four-hectare farm outside Manila," he says. He also has 2,700 chicks, bred from previous winners, which he sells for upwards of 10,000 pesos a head.

Opening up one of the cages he shows me a mottled-brown cock that has already fought and won. There is not a visible scratch or injury on it: "I have two wins already today, and no losses. It is a good day."

In a small shack at the far corner of the cockpit, 63-year-old Eddie Mateo sits, his eyes strained as he concentrates on the rooster he is holding on his bloody apron. For a flat 250 pesos Mateo, his brother, his sister-in-law or his son will tend to your injured bird. Or tell you that there is no hope, in which case they will help you do what needs to be done.

The Mateos' surgery, the only one at La Loma, is more in keeping with a butcher's shop than a medical facility, and is strewn with saws, scalpels and antibiotics.

"On a slow day we might treat 30 cocks, but long days many, many more," says Mateo, dressed in a dirty vest and a baseball cap. "How many die depends on the fights - sometimes both cocks die, sometimes we have to amputate limbs or put the cocks down afterwards.

"My family have been doing this since 1902," he says, as he threads a needle with string to stitch together the gaping stomach wound of the bird in his lap. "My grandfather taught me, and his father taught him."

the betting has barely let up. Dizon is still sitting in the same chair.

"You need to be rich or very lucky here to gamble and win," he says, as I return to my seat.

Today he has won 30,000 pesos and says he will stop while he's ahead, but he doesn't leave. He is still watching the fights hours later, a nervous man trying to stop himself from placing any more bets.

Everywhere you look at La Loma there seem to be knots of tired men trying to balance their need to bet with their gut feelings about the birds in front of them and, presumably, pressure not to go home empty-handed.

"Gambling on cockfighting is like a religion here," one local tells me. "Christianity first, then gambling. Pray for forgiveness on Sunday, then back here on Monday."

The gambling that takes place just before each fight is frenetic, with complex hand signals passing back and forth between the gamblers and bookies, who are known as for their resemblance to Christ as they stand on their chairs with their arms raised to take bets. Often the gamblers will judge a cock on its height or age but occasionally, Dizon says, "it is simply the look in its eyes".

Beside us, a young man prepares to send one of his birds into the fray. He takes his rooster to a small pit at the back of the arena in which dozens of trainers are comparing birds and deciding which they want to be matched up with.

Having chosen a bird of similar size and age, he and the other trainer go to get the fighting blades attached. It is bad luck to buy a blade that has been on the losing side of a brawl, so most trainers purchase a new one every fight.

Back in the stands, and sitting beside the gate to the fighting pit, the young man cradles his bird in his hands. He, too, looks nervous.

He's led into the pit. Without any build up, the fight begins and, one minute and 20 seconds later is over, his opponent's cock vanquished, his own bird escaping with little more than a gash on one wing.

The floor is swept and a new pair of birds is brought into the pit.

As I make to leave, Reyes is still there, trying to decide when to put his cocks in to fight. It is late in the evening, but the crowd inside La Loma is growing still. There is much rooster blood yet to be spilt before the cock crows, signalling a new day.