DHAKA - US marines arrived to bolster relief efforts in Bangladesh on Friday as concerns mounted for survivors of killer Cyclone Sidr which devastated the disaster-prone nation more than a week ago.

Navy personnel from the USS Kearsarge, anchored close to the southern Bangladesh coast, has begun medical evacuations and transportation of water to some of the worst-affected coastal areas, a US embassy spokesman said.

Comment: Sending in the US military in disaster areas is a strategic maneuver as it gives the US army a much needed goodwill and helps to build bridges with the local military forces. The goodwill is then later used as a bargaining chip when needed.

Two more ships -- the USS Essex and USS Tarawa -- are due to arrive soon, said US Navy spokesman Lt Commander John Daniels, speaking in Washington.

All three ships are carrying helicopters and have medical teams and on board surgical facilities, Daniels said.

A huge military-led aid effort is underway in Bangladesh but officials said logistical problems meant only small amounts of relief are getting through and the pace was slow.

But UN resident coordinator Renata Lok Dessallien said the army believed most victims had now received some aid.

"It is not enough necessarily for everyone but at least they have the first batch and the next batch will be close behind. Every day it has been growing steadily," she told AFP.

More than 3,400 people are confirmed dead after the powerful storm ripped through southern and central districts on November 15. Thousands more are missing feared dead and an estimated 280,000 without shelter.

Villagers told AFP they were enduring intolerable conditions.

"The only thing we have been given in all the days since the cyclone is two kilogrammes of rice and 60 taka (less than a dollar) from the local government officials and we have no food and no drinking water," said Mohammad Dulal, 30, from Garjonbunia village, which lies close to the coast.

The entire village has been washed away by the tidal surge and he and his wife and young son are living on the roadside in a shack made from tree branches and plastic that he scavenged.

"I am very worried about my family. If we do not get help, we will be here for months and the conditions are terrible," he said. About 100 people from his village died in the cyclone.

UN coordinator Dessallien said the lack of fresh drinking water was fuelling fears of an epidemic of water-borne diseases.

"We are concerned about outbreaks of diarrhoea and cholera," she said, adding that all the aid agencies faced a major challenge in targeting relief where it was most needed.

The scale of the devastation meant aid workers were trying to reach as many people with small amounts of aid to sustain them over the next few days.

Tonnes of high-energy biscuits were being dropped by the Bangladesh air force while UNICEF was sending water tankers, mobile water treatment plants, millions of water purification tablets and jerrycans.

People from areas not affected by the cyclone also responded to a call by the head of the interim government, Fakhruddin Ahmed, to help their compatriots.

Farmer Mohammed Emadul Haq, 52, told AFP he volunteered to help remove tree trunks from blocked canals and waterways.

"We are Bangladeshis, and it's our responsibility to help however we can," he said.

Another volunteer, businessman Swapan Das, said he and a group of colleagues had collected 500,000 taka (7,140 dollars) to create aid packages for victims -- the sum is a fortune in Bangladesh where 40 percent of the population lives on less than a dollar a day.

Bangladesh has so far received offers of more than 200 million dollars' worth of aid.