“As of now, personally, I am not so sure that we’ve reached every single portion of the territory where people are in need of aid,” he said.

“And, in fact, I wouldn’t be surprised that unfortunately that there might still be, as I’m speaking to you, day 11 of this disaster, there might be still very isolated islands.”

Orla Fagan, a spokeswoman for the UN Office for the Co-ordination of Humanitarian Affairs, said it was a “logistical nightmare” to get relief supplies out at all.

“The size, the quantity of people that have been affected by this, this is massive, between 10 and 12.9 million people have to be assisted to recover from this. This is absolutely huge. It’s like taking the whole of Belgium and trying to assist.”

Aquino visited the town of Palo, just south of worst-hit Tacloban city, where engineers have salvaged generators from a flood IT park to light up the streets and town hall again.

“One is tempted to despair, but the minute I despair, then everybody, it cascades down and everybody gets hampered in their efforts,” he said.

The World Bank is to extend a US$500 million emergency loan to support reconstruction of buildings that can withstand winds of 250 to 280km/h and resist severe flooding, it said in a statement.

Haiyan slammed central Philippine islands with 314km/h winds, causing tsunami-like storm surges that swallowed nearly the whole of Tacloban, once home to 220,000 people, in Leyte and Guiuan town in Eastern Samar.

Nearly 95 per cent of the deaths from the typhoon came from Leyte and Eastern Samar.

Budget Secretary Florencio Abad said the cost of rebuilding would be huge.

“It will be much more than the US$500 million (from the World Bank), even the additional US$500 million that the ADB (Asian Development Bank) is also promising to provide us,” he said.

Video: Philippines buries dead as survivors beg for help

"I'm thirsty and hungry. I'm worried - no food, no house, no water, no money," said ambulance driver Estember, 50.

Thousands of other people who sought shelter under the solid roof of the Tacloban City Astrodome also have to improvise, taking water from wherever they can - a broken water pipe or a crumpled tarpaulin. The water may be salty and foul tasting but it is all many have had for days.

It took several days for aid groups to bring large quantities of water to Tacloban, the eastern Philippine city where the typhoon wreaked its worst destruction. By Friday, tankers were arriving. Philippine Red Cross workers sluiced water into enormous plastic bladders attached to taps from which people filled jerry cans, buckets, bottles and other containers.

"I'm thirsty," said Lydia Advincula, 54, who for the last few days had been placing buckets outdoors to catch rain from some of the torrential downpours that have added to the misery of homeless storm survivors.

Water provisioning should get a big boost with the recent arrival of the US Navy aircraft carrier USS George Washington, a virtual floating city with a distillation plant that can produce 1.5 million litres of fresh water per day - enough to supply 2,000 homes, according to the ship's website. Britain is sending an aircraft carrier, the HMS Illustrious, with seven helicopters and facilities to produce fresh water, Britain's Ministry of Defence said. The ship is expected to reach the area next Monday.

Longer-term water solutions will come once the crucial issues of shelter and security are settled and will probably have to wait several months, said John Saunders, of the US-based International Association of Emergency Managers.

Long-term solutions are a distant concern for Jaime Llanera, 44, as he stands in a shelter he and his family have fashioned out of broken plywood and a tarpaulin.

A single 500-millilitre bottle of mineral water delivered by the military three days earlier is all that's available for his parents, sister, brother-in-law and a friend. To stretch their supply, they've been collecting rainwater and boiling it. They are also using rainwater to clean their clothes.

The family plans to wait one more week. If help hasn't come by then, they'll try to find a way out of Tacloban and stay with relatives elsewhere.

"We have no house. We have no home. But we're still intact," Llanera said.