Desperate survivors cried out for aid on Thursday nearly a week after Cyclone Nargis killed up to 100,000 people, as pressure piled up on Burma to throw its doors open to an international relief operation.

The United States was still awaiting approval from Burma's junta to start military aid flights, but the U.N. food agency and Red Cross/Red Crescent said they have started flying in emergency relief after some delays.

U.S. ambassador Eric John told a news conference in Bangkok that the United States and Thailand had thought the Burma generals had agreed to let a U.S military cargo plane fly in supplies.

But that turned out to be premature.

"We don't have permission yet for the C-130 to go in, but I emphasise 'yet'" John said.

Approval for such a flight would be surprising given the huge distrust and acrimony between the former Burma's generals and Washington, which has imposed tough sanctions to try to end decades of military rule.

Aid has barely trickled into one of the world's most isolated and impoverished countries, although experts feared it would be too little to cope with the aftermath of Nargis, which left up to 100,000 feared dead and one million homeless.

Witnesses saw little evidence of a relief effort under way in the hard-hit Irrawaddy delta region.

"We'll starve to death, if nothing is sent to us," said Zaw Win, a 32-year-old fisherman who waded through floating corpses to find a boat for the two-hour journey to Bogalay, a town where the government said 10,000 people were killed.

"We need food, water, clothes and shelter," he told a Reuters reporter.

AID PLANES ARRIVE

The storm pulverised the delta on Saturday with 190 km winds followed by a massive tidal wave that caused most of the casualties and damage, virtually destroying some villages. It was the worst cyclone in Asia since 1991, when 143,000 people were killed in neighbouring Bangladesh.

U.N. officials, who had earlier complained that an airlift of emergency supplies for the victims was being delayed, said several cargo planes had now landed at Yangon's airport.

WFP spokesman Paul Risley in Bangkok said a Thai cargo plane delivered seven tons of high-energy biscuits and a U.N. chartered flight from Brindisi, Italy arrived in Yangon with water, plastic sheeting, medical kits and other equipment.

He said one other charter flight in Bangkok was awaiting landing clearance permission and a fourth flight was expected to leave from Dubai on Thursday.

The Red Cross/Red Crescent confirmed its first aid plane took off from Kuala Lumpur, carrying six tonnes of shelter materials.

"It's a modest amount, but we hope once we established it, others will follow," an official said. "Another eight tonnes of shelter goods will leave on a Thai commercial flight tonight."

Medicins sans Frontieres, which has 1,000 people in Burma, said it was ferrying aid supplies into the delta via trucks and boats. It said it had been granted permission to fly in supplies.

"We are focusing on those still alive; 50 percent of them have wounds and they are infected," MSF official Frank Smithius in Burma told Australian radio. "Because of the winds and high water, people got smashed around."

Jean-Michel Grand, executive director of Action contra la Faim in London said the logistical obstacles were formidable.

"The roads are very poor or destroyed, and in many cases there were no roads before. Everybody's looking at boats as an alternative. It's going to be a massive logistics challenge.

The WFP's Risley said aid agencies normally expect to fly in experts and supplies within 48 hours of a disaster, but nearly a week after this cyclone, few international groups have been able to send reinforcements into Burma.

Thai Prime Minister Samak Sundaravej failed to reach Burma's ruling generals on Thursday after U.S. President George W. Bush asked him to intervene with the junta to expedite the international aid effort.

"We couldn't reach them because the communication towers have been damaged," Thai government spokesman Wichianchot Sukchotrat told reporters.

State media had reported a death toll of 22,980 with 42,119 missing as of Tuesday, but diplomats and disaster experts said the real figure is likely to be much higher.

"The information that we're receiving indicates that there may well be over 100,000 deaths in the delta area," said Shari Villarosa, charge d'affaires of the U.S. embassy in Burma.