India's first indigenous nuclear-powered submarine INS Arihant was on Monday flagged off for sea trials from Visakhapatnam harbour by Defence Minister Manohar Parrikar.

INS Arihant, the first in the series of nuclear-powered submarines being manufactured indigenously, is a 6,000-tonne vessel powered by 83 MW pressurised light water reactor, Defence Ministry sources said.

Once inducted, the submarine will help the country complete its nuclear triad giving it the capability to respond to nuclear strikes from sea, land and air-based systems.

Nuclear triad is the ability to fire nuclear-tipped missiles from land, air and sea-based weapon platforms.

Arihant will help India achieve the capability of going into high seas without the need to surface the vessel for a long duration.