At least 21 people are now known to have died after a boat carrying undocumented migrants sank near the Malaysian resort island of Langkawi, near the border with Thailand, BBC reported.

Search and rescue operations have entered their third day. Thirteen people have been rescued but dozens remain missing. The Malaysian Coast Guard estimate about 70 people were on board.

Those on the boat are believed to be among 300 people - mostly Rohingya - who left Myanmar's impoverished Rakhine state two weeks ago, Malaysian authorities said.

Another boat carrying 230 passengers is still missing, according to  BBC.