"When we investigated, the vessel's Indonesian crew abandoned ship and were rescued by the navy, navy spokesman Commander D.K.P. Dassanayake said. "The ship is now being checked by a navy boarding party."
The navy's suspicions were aroused as the ship appeared to be of the type used for arms smuggling by the Tamil Tigers, he said.
Several Tiger arms vessels were detected and sunk by naval action this year.
"We got suspicious as the crew claimed they were drifting due to lack of fuel," Dassanayake said.
The navy is now also checking the ownership of the vessel.
Preliminary investigations are done at sea and the vessel will be brought into a nearby port for further investigations."
Updated