Intercepted ... A handout photo released by the Dutch Defence ministry shows one of the two Russian SU-34 "Fullback" bombers being intercepted by Dutch F-16s over the Baltic Sea on December 8. Pic: AFP/Dutch Ministry of Defence Source: AFP

Poland’s defence minister said he was concerned by the extent of Russia’s recent military activity over the Baltic Sea.

Russian actions in Ukraine have produced the worst east-west tensions since the end of the Cold War.

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On Monday, Dutch F-16 fighters intercepted two Russian bombers over the Baltic Sea as part of their participation in NATO’s Baltic air policing mission.

Intercepted ... A handout photo released by the Dutch Defence ministry shows one of the two Russian SU-34 "Fullback" bombers being intercepted by Dutch F-16s over the Baltic Sea on December 8. Pic: AFP/Dutch Ministry of Defence Source: AFP

All told, more than 30 Russian aircraft were intercepted in international airspace “over the Baltic Sea and off the coast of Norway” on Monday, a NATO spokesman said.

“For a few days now, there has been unprecedented Russian activity, from its Baltic fleet to flights over the Baltic Sea,” Defence Minister Tomasz Siemoniak told Polish broadcaster TVN24.

“We’re concerned by this. NATO is working on preparing some kind of response.”

Poland and the Baltics — Estonia, Latvia and Lithuania — have been on edge since Russia annexed the Crimean peninsula from Ukraine and offered support for rebels battling government forces in eastern Ukraine.

NATO has deployed more aircraft, ships and personnel in a bid to reassure the four countries, all new members formerly dominated by Moscow.

There have been around 400 intercepts of Russian military flights near NATO member countries this year, the Western defence alliance said last month.

Lithuania put its military on higher alert on Monday after 22 Russian warships were spotted in the Baltic Sea.