Sri Lanka's Navy says it has rescued 138 Bangladeshi and Burmese nationals from a sinking fishing boat in an operation lasting about 20 hours.
Fishermen alerted the navy after spotting the boat adrift about 80km (50 miles) off Sri Lanka's eastern coast, a spokesman said.
Three ships were deployed. They found one dead person on board. Many others are being treated for dehydration.
Sri Lanka has recently increased naval patrols to intercept migrant boats.
Boat accidents of this nature are not uncommon in Bangladesh, analysts say.
Human traffickers often lure illegal job seekers with promises of lucrative employment in Malaysia, Thailand and other South East Asian nations and take them in overloaded boats.
Fourteen people in the group rescued on Sunday are reportedly from Burma, with the rest coming from Bangladesh. Several women and children were among the survivors.
The navy spokesman said the boat had been adrift for 10 days, but it was unclear where those on board had started their journey from or what their destination was.
Some of those rescued said that when the boat neared Thailand, it was stopped by the Thai Coastguard.
The survivors alleged that they were beaten by the Thais, who confiscated their belongings, throwing them into the sea, before sending the boat on its way.
The account cannot be independently verified.
Many members of Burma's Muslim Rohingya group have been been trying to flee in the past few months, after ethnic violence in the Burmese state of Rakhine left tens of thousands displaced.