At least 10 persons were killed after a boat carrying 20 passengers capsized in the sea off Kalutara in Sri Lanka on Sunday, the navy said.

The boat had sailed from the shores of Beruwala and capsized one and a half nautical miles away from the shore, Xinhua news agency reported.

Navy spokesperson Lieutenant Commander Chaminda Walakuluge said the navy had recovered 10 bodies and deployed six boats, divers and a rescue operation to find the remaining passengers.

Walakuluge said local people in the area were also assisting in the rescue efforts.

The navy said the boat was overloaded with passengers and had not followed the safety regulations.

"When people travel in boats for leisure purposes, the navy and the coastguard have to be informed. The boats which capsized had not followed any safety regulations as the bodies recovered did not have life jackets," Walakuluge said.

The spokesperson added the ill-fated boat was a fishing trawler which had been used for leisure purposes.