DHAKA - U.S. military helicopters and Bangladesh air-force planes intensified relief operations on Tuesday in the cyclone-ravaged country as attention turned from rescue efforts to getting survivors back on their feet.

The aircraft dropped food, water and medicine to tens of thousands of people along the country's devastated coast.

"It looks like a war to save people, mostly living under the open sky, from being battered by hunger and cold and disease," said a witness at Barguna district, one of the hardest hit by the November 15th's Cyclone Sidr and its aftermath.

Sidr struck the impoverished South Asian country with 250 kph (155 mph) winds and a 5-metre (16-foot) tidal surge. It killed about 3,500 people, left thousands missing or injured, and displaced more than 2 million.

It came as low-lying Bangladesh was still working to deal with the effects of widespread flooding just months before.

"Now we have lost everything ... (we) are trying to recover from the trauma and rebuild lives," said Barguna villager Mohammad Hatem.

Helicopters from the U.S. navy's Kearsarge, anchored off the coast, started to airlift drinking water on Monday to survivors in the worst-hit districts of Doblar Char, Bagherat and Barguna.

Reporters in Barguna and other devastated areas said despite the massive aid operation many people had still received no relief goods, although with deliveries increasing that situation should end soon.

Some survivors said they were pleased and impressed with the scale of operations in the last few days, after the U.S. helicopters joined the efforts following what was criticised as a slow start.

A defence analyst who requested anonymity said the U.S. participation was "somewhat delayed" because Bangladesh was in a strategic area and its neighbours, which include China and India, did not necessarily welcome the American warships.

"Some Asian powers do not like to see the U.S. operating in this sensitive military area," a defence analyst, who asked not be identified, told Reuters.

The government said the U.S. navy will stay in Bangladesh as long as needed but not a day longer.

Officials in the cyclone areas said the focus was shifting to protecting the survivors and helping them stand on their feet as the period of rescue and mourning ends.

"They have buried their people who died and stopped looking for those still missing, as the main issue for them now is to live," said journalist Aroop Talukder in Barisal, site of a temporary headquarters for the relief operation.

Relief supplies are being flown into the capital, Dhaka, from all over the world, including food, water, blankets and medicines, airport officials said.

Pakistan and India, nearby nuclear rivals whose relations with Bangladesh have not always been smooth, are among those helping.

"It's an all-out efforts to assist the victims of the worst cyclone to live and start a new life," a relief official said.