NEW DELHI, INDIA - An Indian warship on Sunday foiled an attempt by Somalian pirates to hijack merchant vessels off Somalia's coast in in the Gulf of Aden, a navy spokesman said on Monday.

P.V.S. Satish said marine commandos on board the destroyer-class warship boarded a high-speed boat after it tried to close in on 12 merchant vessels including an Indian ship in the piracy-infested waters.

The vessel deployed in the Gulf of Eden on an anti-piracy mission since July was escorting the flotilla when the rogue boat was spotted some 180 kilometres (112 miles) off the Somalian coast, Satish said.

"A cache of arms and several fuel drums and ship boarding equipment were found," the spokesman said in a statement issued from New Delhi, adding that seven Somalians and a Yemeni national on board the boat were disarmed.

"This is the 16th piracy attack that has been prevented and not a single ship under escort of Indian navy has fallen prey to pirates," the statement added.

Piracy is a major problem off the coast of lawless Somalia and the horn of Africa, with heavily-armed militants hijacking commercial ships for ransom.

An international flotilla of warships has been patrolling the Gulf of Aden, which is one of the world's busiest maritime routes.