NEW DELHI - India's first indigenous armed nuclear submarine, INS Arihant, is undergoing sea trials and will be inducted into the Navy after that, a top naval official has said.

"INS Arihant is now undergoing sea acceptance trails as it had already passed several deep sea diving drills. The submarine will be commissioned after completing all the sea trials," Flag Officer Commanding-in-Chief of Eastern Naval Command, Vice-Admiral H.C.S. Bisht, told the media Sunday.

INS Arihant is the lead ship of India's Arihant class of nuclear-powered ballistic missile submarines, which is to be the first of the expected five in the class of submarines designed and constructed as a part of the Indian Navy's secretive Advanced Technology Vessel (ATV) project.

While its 100-member crew have been trained by Russian specialists, Indian scientists at the Bhabha Atomic Research Centre have developed a significant expertise in reducing the size of the reactor to help it fit into the 33 feet diameter hull of the submarine.

Experts say the launch of Arihant will strengthen India's endeavour to build a credible nuclear triad - the capability to fire nuclear weapons from air, land and sea.