The trawler, the Elektron, was boarded by the inspectors near Svalbard islands on suspicion of illegal fishing.

But instead of heading to Norway as directed, it fled to Russian waters.

It was chased by Norwegian coastguards until it reached Russian territory.

The two inspectors spent five days on board the trawler before they were handed back to the Norwegian authorities by a Russian rescue ship.

The prosecutor of the northern Murmansk region, where the Elektron returned to, confirmed a criminal case was being opened on the basis of information supplied by Norway.

"According to the Norwegians, a check revealed a number of serious violations," a statement said.