A boat carrying about 80 Indonesians has sunk off the southern coast of Malaysia after colliding with a patrol boat out to arrest illegal workers, a Malaysian maritime official said.

A spokesman for the Malaysian Maritime Enforcement Agency (MMEA) said two passengers were confirmed drowned, while around 17 remained missing.

At least 61 people have been rescued, local sources told Al Jazeera. 

Search and rescue operations were still ongoing in the waters off Tanjung Piai in the southern state of Johor, the spokesman said.

"We are working with the police, marine officials and public defence department to find the rest."

Local newspapers described the passengers as illegal Indonesian workers and said that the boat was en route to Indonesia.

Malaysian maritime authorities have been engaged in ongoing operations to intercept an expected increase in immigrant traffic as people go home for the Muslim holiday of Eid. 

Al Jazeera's Stephanie Scawen, reporting from Johor Baru, said that the sinking of the ship is the third latest incident in weeks.

In June, an overloaded boat carrying suspected Indonesian immigrants sank as it left Malaysia's west coast, killing at least 10 passengers.

Malaysia, one of Southeast Asia's wealthier economies, has long been a magnet for illegal immigrants from Indonesia and other poorer countries in the region.

Many undocumented Indonesians work in Malaysia's extensive oil palm plantations, a mainstay of its economy.

Source: Al Jazeera and agencies