The Russian Navy's Northern Fleet is carrying out flight tests and warfare trials of its modified Kamov Ka-27M anti-submarine helicopter from large destroyers, the fleet's spokesman, Captain Vadim Serga, said on Monday.

"The modernized Ka-27M (NATO codename Helix) is completing deck landings on a ship as well as trials of its main systems," he said.

The Ka-27M has already undertaken deck landing trials on a stationary destroyer at a berth on the Kola Peninsula, he added.

The latest sea trials will involve tests of the Ka-27M's new avionics systems in search of submarines, and trials of its radar against submarine, surface and air targets.

"The new machine has not only had modern avionics systems installed, but also updated special missions systems," he said. In addition, it has a new radar giving 360 degree coverage and a greater search radius and simultaneous tracking of dozens of targets.

"The modernized Ka-27M has also had its service life extended by another 10 to 15 years," Serga added.

The Ka-27 entered service with the Soviet Navy in 1982 in an anti-submarine role. Variants include the downgraded Ka-28 export model, the Ka-29 transport helicopter and Ka-31 airborne early warning system.

It is fitted with a dipping sonar system as well as sonobuoys, and can be armed with depth charges and torpedos.