At least 13 people have drowned after a small wooden boat carrying about 70 Indonesian migrants sank in the Malacca Strait early on Thursday.
The vessel went down in choppy waters off Malaysia's western coast near the coastal town of Sabak Bernam in central Selangor state, Mohamad Aliyas Hamdan, the local head of the Malaysian Maritime Enforcement Agency said.
"Local fishermen have rescued 13 people and have found 13 bodies," he said.
Based on the size of the boat, it could have been carrying about 70 people but local fishermen said there could have been up to 100 migrants on board, he added.
"We have deployed 12 ships and a plane along with some 200 officers to carry out the search and rescue operation for the remaining victims," he said.
The authorities have yet to interview the victims to confirm their nationality. The bodies will be taken to taken to a public hospital Teluk Intan in neighbouring Perak state.
"We are not sure if the migrants were attempting to land in Malaysia or trying to leave Malaysia illegally," Aliyas said, describing the sinking as the worst boat tragedy so far this year.
Malaysia, Southeast Asia's third largest economy, has been a magnet for Indonesians in search of jobs.
Around two million illegal immigrants -- the vast majority of them from Indonesia -- are estimated to be working in Malaysia.
But maritime accidents are frequent as thousands attempt the perilous sea crossing, despite the risks, to seek low-paying jobs -- typically shunned by Malaysians -- on plantations, construction sites and in factories.
Indonesians often add to the risk by choosing to cross the Malacca Strait in darkness to avoid detection.
Last June an overloaded boat carrying 97 Indonesian migrants heading home for Ramadan sank overnight in rough seas off western Malaysia resulting the death of more than a dozen people.