A major Russian shipyard that specialises in building non-nuclear submarines said its general director had died suddenly on Saturday after 11 years in the job, but gave no details.

Admiralty Shipyards, based in the western port of St Petersburg, announced the death of Alexander Buzakov in a statement. He had been in the job since August 2012.

His main achievement, it said, had been preserving and strengthening the shipyard's order books for modern non-nuclear submarines, surface ships and deep water vehicles.

Tass news agency said the shipyard is building improved Kilo-class diesel-powered submarines capable of launching Kalibr cruise missiles.

In April, Moscow said it had used a diesel submarine in the Black Sea to strike Ukrainian military targets with Kalibrs.

The shipyard said Buzakov graduated in 1980 and had more than 40 years of experience, indicating he had been in his mid-sixties when he died. St Petersburg is the home city of President Vladimir Putin. (Reuters via CNN)

•PHOTO:People attend a ceremony launching the diesel-electric submarine "Rostov-on-Don" at the Admiralty Shipyards in St. Petersburg, June 26, 2014. REUTERS/Alexander Demianchuk/File Photo