Burmese asylum seekers rescued by Sri Lanka's navy last week said they floated at sea for 25 days and 97 people died of starvation after Thailand's navy intercepted them and forcibly removed their boat's engine. The Thai navy has denied the allegation.

Thirty-two men and a boy now held at an immigration detention centre near Sri Lanka's capital, Colombo, were rescued last Saturday when their dilapidated wooden vessel began sinking while making a perilous journey to Malaysia.

All are Rohingya Muslims who face heavy discrimination in Burma, and say they do not want to return there.

The survivors were suffering from serious dehydration when they were rescued about 250 miles off Sri Lanka's east coast. The Sri Lankan navy said it was alerted to the sinking vessel by a fisherman.

"The journey was dangerous, but we had to do that ... as we fear for our lives, no jobs, and big fighting [in Burma]," one of the survivors, Shofiulla, said.

Sectarian violence in western Burma has killed hundreds of people and displaced 100,000 more since last June. The Rohingya speak a Bengali dialect and resemble Bangladeshis, with darker skin than most people in Burma, which is mostly Buddhist. They are widely regarded as illegal immigrants from Bangladesh.

The United Nations estimates the Rohingya population in Burma at 800,000, but the Burmese government does not recognise them as one of the country's 135 ethnic groups. Most are denied citizenship and have no passports, though many of their families have lived in the country for generations. Bangladesh also refuses to accept them as citizens.

The UN High Commissioner for Refugees expressed concern on Friday over the rising number of deaths of Rohingya at sea and urged Burma's government to promote reconciliation in conflict-hit Rakhine state and ensure them basic living conditions and eventual access to citizenship.

While commending the Sri Lankan navy's quick response, UNHCR also said there were continuing reports of some countries in the region putting boat people back to sea. It asked countries to "keep their borders open to people in need of international protection ... (and) offer them temporary assistance and protection until durable solutions can be found."

Shofiulla, 24, said 130 people were on the boat when the journey to Malaysia began on 10 January. They had paid $465 each.

After 10 days' travel, he said the boat reached the Thai border and two boats from the Thai navy intercepted them. Shofiulla said the navy personnel took their engine.

"Then we (had) no food, no rations ... no water. We drank only sea water," he said, adding that the bodies of the 97 who died over the next 25 days were put into the sea.

Colonel Thanathip Sawangsaeng, a Thailand Defence Ministry spokesman, denied the allegations.

"This is absolutely not true. The Thai navy officers would not have done that," he said, adding that similar accusations have been made in the past, including claims that the Thai navy had abused refugees. "The Royal Thai Navy commander has previously made it clear that the Thai officers have treated the boat people according to humanitarian principles.

"There are two approaches in handling the Rohingya: giving them food and help before letting them carry on their sea journey or prosecute them for illegal entry. However, it's not possible that the Thai navy would have done what they were alleged of doing."

The Thai army said last month that it had suspended two senior officers pending an investigation into their alleged involvement in trafficking Rohingya people from Burma to other countries.

Shofiulla said he is a second-year student studying microbiology, but that his university was closed last July after the violence erupted. "We can't go back to our country ... our government kills Muslims ... we are afraid to go back. We want to go to a safe place," said Shofiulla, who appeared to be the only English-speaking person in the group.

He said they wanted to go to Malaysia to find jobs, following in the footsteps of others from his village. He said 25 people were now in the detention centre while eight others were still hospitalised.

Sri Lankan immigration and emigration controller Chulananda Perera said his department had informed Burma's embassy in Colombo and was seeking its cooperation in identifying the survivors to begin the process of sending them back, but has not received a response.

There was no immediate comment from the embassy.