KUALA LUMPUR (AFP) - Malaysian rescuers have recovered the bodies of 35 more Indonesian migrants killed when their boat sank three days ago, along with another survivor, taking the toll in the disaster to 50, officials said on Sunday.

The survivor was recovered on Friday afternoon having spent more than a day in the water and was said to be in good health.

"Thirty-five more bodies have been recovered since Friday," said Mohamad Aliyas Hamdan, a Malaysian Maritime Enforcement Agency official.

"We expect to find more over the next few days," he added.

Aliyas said the search operation would continue for the next three days, adding that from information gained from the 20 people rescued, there were believed to have been up to 80 people on the small vessel.

Officials have said the overcrowded wooden boat capsized and sank in rough seas about 16km off the coast of central Malaysia's Selangor state before dawn on Thursday.

The group were leaving Malaysia to return to Indonesia across the Malacca Strait.

Malaysia is South-east Asia's third-largest economy and a magnet for migrant workers from its poorer neighbours, with the vast majority coming from Indonesia.

About two million Indonesians are now in Malaysia working a range of low-paid jobs.

Deadly accidents in the Strait are not uncommon, however, with travellers typically attempting the crossing in rickety vessels, often at night to avoid detection.

In June 2014, more than a dozen people drowned when a boat overloaded with around 100 Indonesians sank while taking its passengers home for the Islamic fasting month of Ramadan.