From correspondents in Moscow, Russia, 08:30 PM IST

The death toll rose to seven Friday after a gas blast sparked a fire onboard a cargo ship docked for repairs in Russia's European exclave of Kaliningrad.

Three workers were still presumed missing, a Russian navy spokesman Igor Dygalo at the military port was quoted as saying Friday.

Investigators blamed the explosion late Thursday afternoon on a 'violation of safety rules during repair work on the fuel tank,' a source close to the inquiry said.

Russian television showed a fire and smoke billowing from the freighter's deck in the military dockyard off the Baltic Sea.

Dygalo said the cargo ship belonged to a private St Petersburg company who had leased the docks from the Russian navy in the closed port town near the city of Kaliningrad.

(Staff Writer, © IANS)