Dhaka: Dozens are missing and feared drowned after a boat packed with Rohingya fleeing violence in Myanmar and trying to reach Bangladesh sank in a border river Monday, reports and a Bangladeshi fisherman said.

Thousands of Rohingya, a stateless ethnic minority, have arrived in Bangladesh after an outbreak of violence in western Myanmar, where the military is alleged to have committed mass rape and murder and burned villages.

A Bangladeshi fisherman said he had rescued one woman who told him her "overcrowded" boat had sunk in the Naf river after it was chased by a Myanmar army speedboat.

"We heard a woman's desperate cry for help in the morning while we were fishing in the Naf. We quickly paddled to the spot and saw she was fighting to stay afloat," fisherman Suman Das told AFP by phone.

"The woman told us that their boat was overcrowded with Rohingya villagers who tried to cross the river to enter Bangladesh."

The woman did not know what had happened to the others and Das could not say how many people were on the boat.

But the private UNB news agency, quoting a Bangladeshi village councillor, said there were at least 31 Rohingya on board.

A Rohingya source told AFP by phone that the bodies of 13 women and children, two of whom had bullet wounds, had washed ashore in his village on Myanmar's side of the Naf.

This could not be independently confirmed, however, and Bangladesh police and border guards said they were not aware of the disaster.

An estimated 30,000 Rohingya have been forced to leave their homes since a bloody October crackdown by the Myanmar army in Rakhine state, where many of them live.

At least 10,000 have arrived in Bangladesh, the United Nations said last week, although Bangladesh says it has prevented large numbers from entering.

Myanmar has denied allegations of abuse, but has also banned foreign journalists and independent investigators from accessing the area to investigate.