The navy statement said that they had seen the men on the ship's deck with rocket-propelled grenade launchers and guns. The pirates threatened to blow up the warship, and then opened fire.

The naval statement said: "On repeated calls, the vessel's threatening response was that she would blow up the naval warship. The INS Tabar retaliated in self defence and opened fire on the mother vessel.
   
"As a result of the firing by INS Tabar, fire broke out on the [Somali] vessel and explosions were heard, possibly due to exploding ammunition that was stored on the vessel."

'Anti-piracy mission'

India deployed the INS Tabar to escort Indian ships after the country's shipping firms said they were losing $450,000 a month on cost overruns and delays in meeting deadlines.

This would be the third attack the INS Tabar has fended off since it began its anti-piracy mission in the Gulf of Aden on Novermber 2.

Naval commandos flying in a helicopter foiled an attempt to hijack an Indian merchant ship on November 11.

The attack took place 285 nautical miles southwest off the Omani city of Salalah.