Mumbai, Sep 16 (IANS) The Indian Navy foiled an attempt by pirates to storm six merchant vessels off the Yemen coast, an official said Thursday. It is the third such case in four days.

"While on an anti-piracy escort mission in the Gulf of Aden, INS Delhi successfully neutralised another pirate boat Wednesday," a defence ministry spokesperson said.

INS Delhi was escorting the six vessels with 40 Indians among the 147 crew on board. A dhow was detected approaching the ships around 10 a.m. Wednesday, 108 km south of the Yemen coast.

"Marine commandos intercepted the dhow and found a cache of arms including a 7.62 mm rifle, six Rocket Propelled Grenades and ammunition on board," he added. The dhow was disarmed immediately.

"This was the fourth such action taken by INS Delhi in September, three being in the last four days. The escort vessel disarmed pirate boats Sep 5, 12 and 13."

The Indian Navy started anti-piracy operations in October 2008. "This is the 18th piracy attack that has been prevented since then."

The Indian Navy has escorted over 1,200 ships in the region so far.