COX'S BAZAR, BANGLADESH (AFP) - At least five children drowned when boats carrying Rohingya refugees fleeing violence in Myanmar sank early on Wednesday (Sept 6), Bangladesh border guards told AFP.

Authorities said three to four boats had sunk at the mouth of the Naf river, which divides Bangladesh and Myanmar's violence-wracked Rakhine state, raising fears there could be many more casualties.

Scores of people have already been killed attempting to cross the Naf border river since a fresh upsurge in violence in Rakhine on Aug 25, many using small fishing boats unsuited to the rough coastal waters.

Border Guard Bangladesh officer Aloysius Sangma said three to four boats packed with Rohingya refugees had gone down early Wednesday.

"So far, the bodies of five male and female children have been found at different locations," he told AFP.

Local police chief Main Uddin said authorities were travelling to the spot to investigate.

More than 125,000 refugees have flooded across the border into Bangladesh.

Most are Rohingya, a Muslim ethnic minority that the government of Buddhist-majority Myanmar largely does not recognise as citizens.