In Khlong Toey, as elsewhere in Thailand, the impact was quickly felt on the street. Footpath dealers vanished, prices soared and tens of thousands of addicts enrolled at government-run rehabilitation centres. By 2005, national seizures of methamphetamine pills were below 20 million, down from a peak of almost 100 million in 2002.

For Wanlop Hirikul, 52, a community leader and radio broadcaster, it was a period of hope. 'During the Thaksin era, that was a bad time for drug dealers,' he said.

But that era ended with the military's removal of Thaksin last year. Today, say community leaders, the dealers are back on the streets of Khlong Toey, taking advantage of Thailand's political distractions, inept interim leadership and police reluctance to be seen fighting dirty as investigators probe the 2003 crackdown. Rehab centres are seeing more methamphetamine addicts, mostly young people who steal to pay for pills that they smoke or swallow.

'This year it's getting worse. The drugs are coming back to our community ... where there used to be one dealer on the street, now there are three,' said Mr Wanlop.

National anti-drugs officials have sounded similar warnings. Pitthaya Jinawat, deputy chief of the Office of the Narcotics Control Bureau (ONCB), said recently that political instability had emboldened traffickers. Last year, Thailand reported a 40 per cent yearly rise in drug-related cases to 68,450.

As alarm grows in poor communities over rising drug use, Thaksin's political successors are calling for another crackdown. On the campaign trail ahead of the December 23 parliamentary election - the first since September 2006's coup - the pro-Thaksin People's Power Party (PPP) is touting its anti-drugs credentials ahead of its rivals. Politicians have promised to take the fight to the traffickers at their rallies.

Chalerm Yubamrung, a veteran Bangkok politician and deputy leader of PPP, has vowed to revive Thaksin's get-tough eradication policy if elected to office. 'We will declare a new phase in the war on drugs,' he told the Bangkok Post. Asked about state-sanctioned slayings under Thaksin, Mr Chalerm, who has his eyes on the interior ministry portfolio, said it was a 'misunderstanding' that wouldn't be repeated.

Among the victims in 2003 was a nine-year-old boy known as Fluke, whose father, a small-time dealer in Khlong Toey, was trapped in a police sting. Fluke's mother tried to escape by car, but police caught up with the vehicle and, after the mother fled on foot, shot into the car, killing the boy.

Earlier this year, the military-appointed government set up a fact-finding panel to investigate this and other human rights abuses during the 2003 crackdown. Its report is due to be released early this month and could form the basis of a human rights prosecution of Thaksin, who is living in exile in London. The panel is also expected to award compensation to families of victims who were unlawfully killed, including that of Fluke.

Community leaders in Khlong Toey say although Thaksin's war on drugs cost the lives of innocents, it was a justifiable response to the traffickers, who were costing Thailand dearly in wasted lives. A rerun may be necessary, they say, if the situation continues to worsen.

'If you think about the 2,000 or more people who died, you should compare that to the effect that they had on the people who bought their drugs, a much larger number,' said Mr Wanlop.

Such calculations are consistent across Thailand, despite the outcry in Bangkok over Thaksin's bloody crackdown. A 2004 survey by the Asia Foundation conducted in several regions, including the Muslim-dominated southernmost states, found widespread acceptance of get-tough policies by law enforcement officers against drug dealers and human traffickers.

An average of 67 per cent of respondents said extrajudicial killings were permissible in such cases. 'Essentially, the ends justified the means,' said James Klein, country director of the Asia Foundation in Thailand.

Chartchai Suthiklom, a senior adviser to the ONCB, said the political fallout over Thaksin's policy shouldn't stop law enforcement officers from taking on traffickers. He said that smuggling of drugs, particularly methamphetamine, into Thailand was on the rise, and should be tackled. 'Aggressive and serious suppression doesn't mean killing people. We can use the law for suppression,' he said.

Although the 2003 crackdown was popular in drug-ravaged Thai communities, it might have unwittingly contributed to worsening situations in neighbouring countries. Interdiction efforts along the Thai-Myanmar border have forced smugglers to explore alternative overland routes into Thailand through Laos and Cambodia, as well as sea routes to Malaysia, according to Jeremy Douglas, a regional project co-ordinator for the UN Office on Drugs and Crime in Bangkok. A recent seizure of 1.2 million pills in Bangladesh that originated in Myanmar also indicates another trafficking route into Southeast Asia, or possibly India.

In recent years, Cambodia and Laos have seen a sharp rise in addiction to methamphetamine and other stimulants, at a time when Thailand's market has been shrinking. 'You could say that Thaksin's war on drugs was a disaster for these countries because the supply routes through the Golden Triangle now go through Laos and Cambodia and to Malaysia. These countries began as transit routes, now they've become consumers. Ya ba is the No1 drug abused in Cambodia,' said Mr Douglas.

By contrast, Hong Kong and the mainland are primarily consumers of crystal meth, although the mainland seized four million methamphetamine pills last year. 'This is a regional problem, it's not just Thailand. Methamphetamine abuse is going on in China, Cambodia, Laos, Philippines and elsewhere,' Mr Douglas said.

That's little comfort to Nittaya Phrompochuanboon, 50, a social worker at the Duang Prateep Foundation, which helps the poor in Khlong Toey. She throws up her hands at the response of local police to the drug dealers who operate in her district. Even when tip-offs are provided, police officers fail to catch dealers in the act, to the frustration of residents.

'How can the police not know who the traffickers are when the neighbours see that they're selling drugs,' she asked.

At night, Ms Nittaya joins a group of volunteers who patrol the district, keeping an eye out for dealers so they can inform the police. But that can be risky as it invites retaliation from local gangsters with a stake in the drugs trade. So tip-offs are sent anonymously by mail or phone, or passed on by trusted emissaries.

Colonel Suthip Palitkusontat, a local police commander, said drug-related arrests in his precinct had been flat in recent years, but he planned to respond to local concerns with night patrols and urine tests for anyone picked up on suspicion of drug dealing.

'Residents are aware of what's going on and there are signs of more dealers in the streets,' he said.

One indicator of increased methamphetamine trafficking is street prices. In 2003, pills sold for as little as 40 baht (HK$10) in Bangkok, tempting many to try them. After the crackdown, prices climbed as high as 300 baht. The current price in Khlong Toey is 150-180 baht.

'If we let the situation go, the price will keep going down,' Ms Nittaya said.

The impact is already being felt among local families. A private centre for treating methamphetamine addicts outside Bangkok that is supported by the Duang Prateep Foundation has seen its intake climb in recent years from 20-30 people to about 50.

Inside a nearby Buddhist temple, a government-run programme for 110 men is under way. Most were sent to the temple after being arrested and testing positive for methamphetamine. They spend two months staying clean, studying meditation and life skills before being sent home, their criminal records purged. With their shaved heads and cream pyjamas, they blend in easily with the temple's saffron-robed monks.

Anon Pasuk, 27, tried methamphetamine for the first time aged 17 when he found his father's supply. He supported a two-pill-a-day habit by dealing to friends in Bangkok while holding down a job as a factory delivery boy. His luck ran out in September when police stopped him on a motorbike and he tested positive.

But having quit, he's ambivalent about his plans to stay clean after he finishes the programme. The temptation is always there, he admits. 'You can find ya ba everywhere, no problem.'