Five crew members were rescued from a small Norwegian-flagged general cargo ship following what could have been an encounter with a Russian warship.

The 1,564-dwt Bjugnfjord (built 1976) was said to be in distress just over 20 km northwest of Gilleleje, Denmark, around 9:30pm local time (2030 GMT), according to the Danish Royal Navy and Swedish Coast Guard. Both forces sent search and rescue teams to the area.

The operation lasted just over an hour. The five seafarers, who had taken to the vessel's lifeboats, were flown to Sweden.

Neither Danish nor Swedish authorities said why the ship was in distress, but maritime security provider EOS Risk said the culprit could be Russia.

“It is a realistic possibility that this incident could have involved a Russian warship,” it said in an alert.

“Russian maritime assets are often aggressive and conduct unsafe manoeuvers in and around the Baltic Sea region.”

The Swedish Coast Guard said it did not know anything about Russian ships in the vicinity of the incident.

It said Denmark was leading the rescue operations.

Earlier in the week, Euractiv reported Russian navy ships were leaving the Baltic Sea, citing a radio interview with a Swedish naval officer.

The officer said the movements were “not strange in itself”.

Other media reports suggest a string of Russian naval ships have left the Baltic Sea this week, with some reaching the English Channel.

Reuters reported on Thursday night that Russia announced its navy would stage a series of drills this month across the globe, including in the Mediterranean Sea, the North Sea and both the Atlantic and Pacific oceans.

The newswire said 140 warships will be involved in the exercises, along with 60 planes and 10,000 servicemen.

The move comes as tensions between Russia and the west over Ukraine continue to rise, with US President Joe Biden warning Moscow that it would pay a "heavy price" for any moves into its eastern neighbour.

He had suggested earlier in the day a response would be weaker if Russia mounted a "minor incursion" but walked the comments back amid a flurry of criticism.

According to Equasis, the Bjugnfjord's registered owner is Fosenfrakt, a Bergen-based company, and its commercial manager is compatriot Lighthouse Ship Management.

TradeWinds called a phone call to a number obtained for Fosenfrakt and was told it was the wrong number.

Lighthouse did not immediately respond to an email seeking comment.