Panaji, Oct 1 (IANS): The Indian Navy is maintaining aerial surveillance on three dhows and an unconfirmed number of skiffs suspected to be manned by sea pirates 600 and 700 nautical miles off the Goa coast, respectively, an officer here said Saturday.

The suspected pirate vessels were under surveillance since Friday and the Indian Navy had dispatched a fleet of armed marine vessels to raid the vessels and verify the antecedents of those on board, flag officer commanding Goa area (FOCGA) rear admiral Sudhir Pillai told reporters here.

"It is an ongoing operation. We have these vessels under observation for 24 hours now. We have sent our boats on a surface operation to board the vessel and check their documentation," Pillai said.

The operation was launched after the Indian Navy was informed about the presence of unidentified crafts by a marine shipping vessel passing through the area Friday.

"We have diverted all marine traffic away from the area. Piracy subsides during the monsoons. But as the monsoons subside movements of pirates begin," the officer said, adding that an IL-38, a maritime surveillance aircraft, was being used to constantly monitor the movements of the vessels.

"The boats are in a suspicious area deep in the sea. That is why we are on alert," he added.