Beijing: In the worst-ever disaster in China's Naval history, 70 sailors were killed in an accident aboard a conventional submarine, an official report said.

The Number 361 submarine was taking part in a drilling East of Nechangshan islands, when mechanical problems caused the accident "recently", Xinhua news agency quoted Navy sources as saying.

The date of the accident was not provided.

The ill-fated submarine has been towed back to the port base, Xinhua said.

Jiang Zemin, former President and chairman of the Central Military Commission, has sent condolence messages to family members of the dead Navy officers and seamen, it said.

PTI