BBC's Clive Myrie: Aid agencies say rellief given so far is not enough to avert disaster

The warning came as the number of people confirmed dead across the region following Hurricane Mitch rose to around 11,000.

With another 13,000 missing and feared dead, Mitch looks set to become the deadliest Atlantic hurricane on record.

Helicopters are deperately needed to save people in remote areas

In Nicaragua, President Arnoldo Aleman announced the number of dead had risen to 3,800 after more bodies of victims from the massive Casitas volcano mudslide turned up.

He said it would take at least one or two years for the country to return to normal.

But the authorities are increasingly worried the number of casualties could soar if they cannot get still more aid airlifted to the highland areas.

Peter Greste: "Urgent food aid is essential if another human catastrophe is to be avoided"

Our correspondent Peter Greste says hundreds of thousands of people in isolated regions cannot realistically expect food or water to come for days.

US announces $70m emergency aid

The growing fears come as the United States, pledged emergency aid of $70m, including 2,800 tons of food, for the hurricane victims.

Brian Atwood describes aid priorities

The head of the US Agency for International Development, Brian Atwood, said $20m of food aid would start arriving at the weekend, as would medicines and other equipment.

"This is just to deal with the humanitarian consequences. This is just to save lives," he added.

Landmine threat

More helicopters and engineers are also being sent out to help rebuild roads and bridges.

Mexico has launched one of the biggest airlifts in its history, and European states have approved a combined $8m in humanitarian aid.

Nicaraguan Foreign Minister Eduardo Montealegre - More international help needed

In addition, French de-mining experts are on their way to Nicaragua to help control an unexpected side effect of the disaster - swollen rivers have exposed thousands of anti-personnel landmines from the civil war in the 1980s.

In Spain, government and campaign groups have gathered $30m to be used on flood relief in just four days.

Severe shortages

George Eykyn: "Whole villages have been submerged in a sea of mud"

Even in the Honduran capital Tegucigalpa, where supplies are being flown in from abroad, there are now severe shortages of food and medicines.

Many in the city died when water swept away shanty towns, and over a million lost their homes.

Their houses have been replaced by mud and the flotsam of wrecked cars, rubble and tree trunks.

Rescue efforts are hampered by flooded roads and collapsed bridges

In more remote areas, the situation is much worse.

Almost 100 bridges are reported to have been destroyed, making the relief effort a logistical nightmare.

Honduras saw more rain in one week than it normally gets in a year.

But officials revised the country's death toll down to 6,076 on Thursday after getting better information from the ravaged countryside.

Threat of disease

Doctors fear epidemics because of the number of dead bodies in rivers.

They are already treating many respiratory and stomach infections, but are running out of antibiotics.

Health workers have been burning bodies and burying others in mass graves in an attempt to prevent the spread of disease.

But near the Casitas volcano they reported finding so many bodies that they were running low on fuel to burn them.