The keels of two submarines destined to join Russia's Black Sea fleet have been laid in a special ceremony attended by the deputy commander of the Russian Navy.

JSC Admiralty Shipyards identified the vessels as the Veliky Novgorod and Kolpino, diesel-electric boats featuring acoustic stealth and an enhanced target detection range.

Other features include an inertial navigation system and an automated information management system.

The two vessels belong to the new Varshavyanka-class of submarine, which is based on a class boats that were introduced into service in the 1980s. A total of six Varshavyanka-class submarines are being procured by the Russian Navy for Black Sea duty.

The Novorossiysk, the first of the Varshavyanka-class (also known as the 636- class) boats -- was transferred to the Russian Navy on October 21. The second, the Rostov-on-Don, is currently undergoing sea trials and is expected to be delivered before the end of the year.

JSC Admiralty Shipyards said the keel laying took place on Thursday, which was the 310th anniversary of the founding of the shipyard during the reign of Czar Peter the First.