New Delhi: Global body-- the World Food Programme (WFP)-- has said it was yet to get permission from the Burmese government to allow the use of a chopper to airlift aid to remote areas in the Irrawaddy delta.

"We have one helicopter available for use now in Rangoon, but it has not been deployed yet," Paul Risley, WFP spokesperson in Bangkok said. "However, It is ready to be pressed into service," he added.

Risley said it was important for them to be able to use the helicopter as several villages in remote areas in the delta were inaccessible due to difficulties in transportation.

The WFP, which has been supplying aid to the cyclone victims, said it has nine more helicopters in Bangkok, awaiting permission from Burma's military rulers--- to be sent into Burma.

Risley said, "We have another nine helicopters currently in Thailand and within a number of days they will be ready to transfer to Burma from Bangkok."

The WFP, which so far has been able to supply an estimated aid to 575,000 cyclone victims, said their aid operation had been delayed due to the government's restrictions on their international aid workers. These workers had to stay for a while in the delta region.

"We want the staff to stay and work in the delta area but we cannot get the requisite permission," Risley said. "This remains a challenge for our work in the delta," he added.

Meanwhile, United States defence officials said four of its naval ships carrying aid supplies and several helicopters would be ordered to leave soon, after failing to obtain permission from the Burmese junta for the past two weeks.

US Defence Secretary Robert M. Gates, during an Asia Security conference in Singapore on Sunday said, "No decision has been made at this point, but the ships obviously have been out there going around in circles for a long time. At this point, it is becoming pretty clear that the regime is not going to let us help."

Last week, the French Navy ship--- 'The Mistral', which had been waiting off the coast of Burma for permission from the ruling junta to allow them to help the cyclone victims, withdrew to Thailand and off-loaded its supplies.

On Saturday, WFP Executive Director Josette Sheeran, who visited the cyclone-hit regions in Burma, urged the Burmese government to do away with the red tapism, which was delaying deployments into the delta.

In a release issued on Sunday after her return from Burma, Sheeran said, the government procedures for clearing the deployment of aid workers remained a constraining factor, reducing effectiveness.

The WFP said while it was able to supply aid to 575,000 people of its target of  6,63,000 with a first ration of rice, "many people have not been reached," adding that the others are now due for a second round of distribution.

An aid worker in Rangoon, who returned from the Kun Chan Kone Township in Rangoon division said, though aid is reaching refugees and cyclone victims in the towns, several villages have been left out due to transportation and communication problems.