Three Russian military reconnaissance aircraft were intercepted over the Baltic Sea by German and British air forces on Wednesday.

"Reconnaissance flights intercepted. German and British Eurofighters were alerted to identify three military aircraft," the German air force said on Twitter.

"The two SU-27 Flankers and an IL-20 from Russia were flying again without transponder signals in international airspace over the Baltic Sea," it added.

As a NATO member, Germany participates in monitoring the airspace over the Baltic states.

Security has been heightened for the Baltic states after Russia invaded Ukraine last year.

Russian military jets have repeatedly strayed into the airspace over the Baltic Sea in recent months.

The Norwegian air force said Tuesday it had similarly identified a group of Russian military aircraft in international airspace over the Barents Sea to the north of the country.

The aircraft included two Tu-160 Blackjack bombers, two Il-78 Midas aerial refueling tankers and three MiG-31 Foxhound fighter jets, the air force said on Facebook.