Construction of the Severodvinsk submarine began in 1993 at the Sevmash Shipyard in the northern Russian city of Severodvinsk but has since been dogged by financial setbacks. It was floated out in June last year.

"The submarine is undergoing harbor trials at the Sevmash Shipyard and is getting ready for sea trials in May," the official said. "It should enter service with the Russian Navy by the end of this year."

Graney class nuclear submarines are designed to launch a variety of long-range cruise missiles (up to 3,100 miles or 5,000 km), with conventional or nuclear warheads, and effectively engage submarines, surface warships and land-based targets.

The submarine's armament includes 24 cruise missiles and eight torpedo launchers, as well as mines and anti-ship missiles.

In 2009, work started on the second sub of the Graney class, the Kazan, which will feature more advanced equipment and weaponry.