The United Nations warned Monday of a quickly mounting death toll from the super typhoon in the Philippines, with 10,000 people feared killed in the worst-hit city of Tacloban alone.

One top humanitarian official said the UN was "expecting the worst" on the final body count, and also cited the desperate need for clean drinking water and food for survivors of the disaster.

John Ging, UN humanitarian operations director, said 660,000 people had fled their homes because of typhoon Haiyan and that the United Nations will appeal for significant international aid for victims on Tuesday.

"The scale of devastation is massive and therefore it will require the mobilization of a massive response," Ging said, praising the Philippines government response to the disaster as "very impressive" so far.

UN humanitarian chief Valerie Amos, who is heading for the Philippines, said in a statement that "local officials estimate that some 10,000 people were killed in one city alone." Her spokeswoman confirmed that she was referring to Tacloban, which was devastated by the storm.

"Many places are strewn with dead bodies," Ging told a news conference at UN headquarters, confirming estimates that "over 10,000 people perished."

Amos was expected in Manila to run a joint relief operation by private groups and the UN, which has already released $25 million from its emergency fund for aid.

Tuesday's "flash appeal" for cash, was likely to be seeking hundreds of millions of dollars, UN officials said.

When asked about Haiyan's final toll, Ging added: "We are certainly expecting the worst. As we get more and more access we find the tragedy of more and more people killed in this typhoon."

Ging told of the battle to get to Tacloban and other areas badly hit by the super typhoon, which swept huge waves and the fiercest storm winds recorded in the past century into the Philippines.

He said it was taking three hours for relief vehicles to cover the 11 kilometers (seven miles) from Tacloban airport into the city.

But the devastation is widespread across Leyte and other provinces, heightening fears of more deaths. The UN humanitarian agency said about 5,000 homes had been destroyed in Cadiz City in Negros Oriental province.

In Iloilo province there was "significant devastation" in the towns of Conception and San Dionisio, the agency added.

"The first priority of response teams, once they were able to navigate their way into these areas, is to mobilize the burial of dead bodies because of the public health issues," Ging said.

Ahead of Tuesday's appeal, UN leader Ban Ki-moon welcomed aid already offered but said contributions "must expand urgently in the days ahead."

UN expects 'the worst' in Philippines typhoon disaster
Tacloban, Philippines (AFP) Nov 11, 2013 - The UN warned it expected "the worst" in the typhoon disaster that devastated the Philippines, saying one town alone may have more than 10,000 dead, adding even more urgency to rescue operations underway Tuesday.

The Manila government has declared a national emergency and desperation was mounting in the central Philippines where countless bodies were scattered across wastelands, four days after the unprecedented havoc wreaked by Super Typhoon Haiyan.

US marines have joined the frantic effort to find and help famished survivors, deploying to a zone where entire towns were flattened and communities were bereft of food, water and medicine.

The United Nations warned Monday the death toll was quickly mounting.

"We are certainly expecting the worst. As we get more and more access we find the tragedy of more and more people killed in this typhoon," a top UN humanitarian official, John Ging, said.

He was unable to give an estimated overall toll for the disaster, telling a news conference at UN headquarters "it is estimated now over 10,000 people perished".

UN humanitarian chief Valerie Amos said in a statement that "local officials estimate that some 10,000 people were killed in one city alone," referring to Tacloban, capital of the eastern province of Leyte.

The United Nations was to appeal for significant international aid for victims on Tuesday.

Relief cannot come soon enough for Joan Lumbre-Wilson, 54, who was among a large crowd of people gathered around one of the few relief centres in the ruined city of Tacloban.

"We want an organised, coordinated brigade to collect the dead bodies, bring food and stop the looting," she said.

"It has been four days. We want water and food. We want someone who will help. We are emotionally drained and physically exhausted. There are many babies and children who need attention."

Filipino President Benigno Aquino late Monday declared a national state of calamity, which allows the government to impose price controls and quickly release emergency funds.

"In the coming days, be assured: help will reach you faster and faster," he said in a televised address.

"My appeal to you all is: remaining calm, praying, cooperating with, and assisting one another are the things that will help us to rise from this calamity."

Haiyan generated waves up to five metres (16 feet) high that surged inland like a tsunami. The walls of water destroyed nearly everything in their path along huge stretches of coastlines throughout the central band of the archipelago.

Philippine authorities have been overwhelmed, their efforts to quickly deliver aid hamstrung by the destruction of airports, roads, bridges and other infrastructure.

Many areas remain cut off from any relief efforts, leaving bodies to rot in the humid atmosphere and survivors little choice but to rummage through the debris for food, water and other essentials.

Even in Tacloban, the base for relief operations in Leyte, bodies remained littered through the streets and the stench of rotting flesh hung thick in the air.

The UN's Ging praised the government response as "very impressive", however he told reporters of the battle to get to Tacloban and other areas.

He said it was taking three hours for relief vehicles to cover the 11 kilometres (seven miles) from Tacloban airport into the city.

The scale of the disaster continued to unfold as more remote areas were surveyed, with aerial photos of Samar island, where Haiyan first made landfall, showing whole districts of coastal towns reduced to piles of splintered wood.

Haiyan's sustained winds when it hit Samar 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.

US marines shocked at devastation

In Tacloban, dozens of American marines arrived on Monday aboard two US military C-130 transport planes packed with relief supplies. They expressed shock after receiving a bird's eye view of the carnage.

"Roads are impassable, trees are all down, posts are down, power is down.... I am not sure how else to describe this destruction," Brigadier General Paul Kennedy, the commanding general of the Okinawa-based 3rd Marine Expeditionary Brigade, told reporters.

The Marine Corps said another 90 troops were on their way, tasked with conducting a humanitarian assistance survey.

The US troops were the most visible sign of a major international relief effort that had only just begun and could last for years, with aid agencies likening the scale of the destruction to the 2010 Haiti earthquake that killed tens of thousands.

"The level of destruction we're seeing reported is absolutely staggering," said Antonio Guterres, head of the UN refugee agency, which usually works only in conflict zones but which was organising an airlift due to the "exceptional nature" of the tragedy.

Many foreign governments have pledged help, with Australia donating nearly US$10 million.

Adding to concerns was a looming storm in the Pacific Ocean that threatened to dump heavy rain across Leyte and other devastated areas.

The depression is expected to hit land on the southern island of Mindanao late Tuesday, then move across the central islands of Bohol, Cebu, Negros and Panay, which all suffered typhoon damage, weather forecaster Connie Dadivas told AFP.

Security forces deployed to contain looters

Meanwhile, hundreds of Filipino police and soldiers were deployed to contain looters in and around Tacloban, after mobs ransacked a Red Cross aid convoy on Sunday and gangs roamed the streets stealing consumer goods such as televisions.

"We have sent substantial (forces) there and if we need to add some more, it won't be just the police but even the armed forces," civil defence office spokesman Reynaldo Balido said on ABS-CBN.

Blaming global warming for the typhoon's ferocity, Philippines negotiator Naderev Sano at UN climate talks in Warsaw pledged to fast until progress was made on tackling the environmental crisis.

Haiyan swept out into the South China Sea on Saturday and hit Vietnam and China on Monday in a significantly weakened state, although still strong enough to uproot trees and tear roofs off hundreds of homes, killing at least five in China.

The Philippines endures a seemingly never-ending pattern of deadly typhoons, earthquakes, volcano eruptions and other natural disasters.

If the death toll of more than 10,000 is correct, Haiyan would be the deadliest natural disaster ever recorded in the country, exceeding the 1976 Moro Gulf tsunami that killed between 5,000 and 8,000 people.