About 130 people are missing, feared dead, after a boat carrying refugees fleeing Burma sank off Bangladesh, according to local police.
One survivor from the sinking on the border between Bangladesh and Burma reported that the boat had about 135 passengers on board.
It was understood to be carrying Muslim Rohingya, who have been described by the United Nations as among the world's most persecuted minorities
They have fled Burma in their hundreds of thousands in the past decade, usually heading into Bangladesh, which estimates it now shelters around 300,000 Rohingya.
Recent unrest has triggered another exodus.
Mohammad Farhad, police inspector at Teknaf on the southeast tip of Bangladesh, said: "The boat was heading to Malaysia illegally."
The 24-year-old survivor was being held in custody. Mr Farhad said: "He does not know what happened to the others as it was dark and he was desperate to save his own life."
Mr Farhad said six survivors were reported to have been picked up by a fishing vessel after the refugee boat left Sabrang village in Bangladesh on Saturday.
Many Rohingya refugees try to head to Muslim-majority Malaysia for a better life.
Chris Lewa, director of The Arakan Project, a Rohingya advocacy group, said: "We learned that an overcrowded boat with 133 people on board, which was leaving for Malaysia, sank. Six survivors have been rescued by fishing boats. The others are missing.”
However, she said, her organisation had been told that the accident happened overnight Monday to Tuesday.
Officials said Bangladesh coastguards had yet to find any bodies after the sinking.
Jasim Uddin, acting administrator of Cox's Bazaar district, said: "We could not start a search and rescue operation as the survivor could not confirm to us the position of the accident. The coastguard is on alert to watch for bodies on the shore."