Maritime authorities in Malaysia say that a boat carrying about 100 people capsized off the western coast of Malaysia on Thursday.
According to local media, the passengers on the boat were believed to be illegal immigrants.
Quoting a spokesman for the Malaysian Maritime Enforcement Agency, Reuters reported that it was not immediately clear if there were any casualties, but that several survivors had been rescued by fishermen.
AFP quoted a Malaysian maritime official as saying 13 were killed and another 13 were rescued by local fishermen.
The news agency reported that the passengers on-board were believed to be Indonesian migrants.
Officials said they had deployed ships and an aeroplane to search for survivors.
The local head of the Malaysian Maritime Enforcement Agency, Mohamad Aliyas Hamdan, told AFP: “We are not sure if the migrants were attempting to land in Malaysia or trying to leave Malaysia illegally.”
Southeast Asian nations in the summer faced a huge migrant crisis, with more than 4,000 landing in Indonesia, Malaysia, Thailand, Myanmar and Bangladesh since Thailand launched a crackdown on people-smuggling gangs in May.
In June 2014 two overloaded boats carrying Indonesian migrants capsized in the same area, killing at least 15 people at that time.