The UN launched an appeal for more than $300 million in aid as US and British warships on Wednesday steamed towards the typhoon-ravaged Philippines, where thousands of people are feared dead.

Five days after Super Typhoon Haiyan destroyed entire coastal communities with record winds and tsunami-like waves, the magnitude of the disaster continued to build with almost unimaginable horror.

Festering bodies still littered the streets in many areas Wednesday, with the smell of rotting flesh hanging in the air and ramping up the fear of disease in the tropical heat.

Increasingly desperate survivors begged for help that was having difficulty reaching them -- many still without access to food and water after nights spent in the open.

UN humanitarian chief Valerie Amos told reporters in Manila the money was needed for "food, health, sanitation, shelter, debris removal and also protection of the most vulnerable".

Amos praised the international community's reaction since Haiyan slammed into the Philippines on Friday, but said much more needed to be done in a disaster of almost biblical proportions.

"We have already seen an international and generous response given the horrific pictures that people have seen, particularly on their television screens," she said.

The UN warned 10,000 people were feared dead in just one city, Tacloban, the provincial capital of Leyte province where five-metre (16-foot) waves flattened nearly everything in their path as they swept hundreds of metres inland.

The UN cited local officials for the estimate.

However, on Tuesday night Philippines President Benigno Aquino said he believed the estimate of 10,000 killed was "too much".

Speaking in a televised CNN interview, he said that local officials who gave that estimate may have been "too close" to the disaster to give an accurate toll.

"Being in the centre of the destruction... there is emotional trauma associated with that particular estimate," he said. "They didn't have basis for it."

He continued: "The figure I have right now is 2,000... so far about 2,000, 2,500 is the figure we're working on", though he admitted the toll still could rise.

It was unclear if Aquino was referring to the toll in the city of Tacloban alone.

On Tuesday night, the official government death toll stood at 1,774, although authorities have said they have not come close to accurately assessing the number of bodies lying amid the rubble or swept out to sea.

'Where is the food?, where is the water?'

Nearly 10 million people, or 10 percent of the Philippines' population, have been affected, while 660,000 have lost their homes, the UN estimated.

Overwhelmed and under-resourced rescue workers have been unable to provide desperately needed food, water, medicines, shelter and other relief supplies to many survivors, and desperation has been building across the disaster zones.

"There is nothing here left for us. Our house is gone, we don't have any money, we don't have our documents, passports, school records," Carol Mampas, 48, told AFP at Tacloban's destroyed airport as she cradled her feverish baby son in a blanket.

"Please, please, tell authorities to help us. Where is the food, where is the water? Where are the military collecting the dead?"

Bodies still litter the wreckage, as gangs take advantage of a security vacuum to loot homes and businesses.

On Tuesday, Philippine troops killed two communist insurgents who attacked an aid convoy en route to Tacloban, the military said.

The government announced a night-time curfew for Tacloban and deployed special forces across the ruined city to try to prevent pillaging.

Heavy rain in Tacloban compounded survivors' desperation, while a tropical storm to the south threatened other typhoon-hit islands where hundreds were also killed.

International aid ratchets up

The United States and Britain announcing they were sending warships carrying thousands of sailors to the Philippines.

The aircraft carrier USS George Washington, which has 5,000 sailors and more than 80 aircraft aboard, headed from Hong Kong to the United States' close Asian ally on Tuesday.

Five other US warships are also being deployed, and the carrier group is expected to reach the Philippines within two to three days, the Pentagon said. Dozens of US marines arrived in Tacloban on Monday as an advance team.

A British warship, currently in Singapore, would head "at full speed" to the Philippines, Prime Minister David Cameron announced on Monday.

Many other countries have pledged help with even China, which has been embroiled in a bitter territorial dispute with the Philippines, offering aid and sympathy.

Aquino has declared a "state of national calamity", allowing the government to impose price controls and quickly release emergency funds.

Haiyan's sustained winds when it hit Samar island, where it first made landfall, reached 315 kilometres (195 miles) an hour, making it the strongest typhoon in the world this year and one of the most powerful ever recorded.

Aerial photos of Samar showed whole districts of coastal towns reduced to piles of splintered wood.

The Philippines is hit with an average of 20 tropical storms or typhoons a year, as they emerge from the Pacific Ocean and sweep west.

However Haiyan's record intensity has fuelled concerns that climate change is increasing the ferocity of storms.

If the death toll of more than 10,000 is correct, Haiyan would be the deadliest natural disaster ever recorded in the country.