Fighter planes from Britain and Norway scrambled on Friday to keep watch on Russian bombers that were approaching the countries' air space, officials said.
The incidents occurred amid high tensions between Britain and Russia, as each country ordered the expulsion of four diplomats from the other side. There was no indication that the fighter plans were connected to the row.
Norwegian military spokesman Lt. Col. John Inge Oeglaend told The Associated Press said his country's F-16s were sent into action twice: once when two Russian Tu-95 bombers headed south along the Norwegian coast in international air space. They turned around above Aberdeen on Scotland's North Sea coast.
In the second, two Tu-160 bombers were spotted flying near Norwegian air space over the Barents Sea, he said.
Oeglaend characterized the incidents as routine and but said it was a "bit unusual that the first two bombers went so far south." Aberdeen's latitude is about 80 kilometers (50 miles) below the southern tip of Norway.
Russian Air Force spokesman Col. Alexander Drobyshevsky said British and Norwegian planes approaching bombers on training flights were a "normal occurrence."
A spokesman for Britain's Royal Air Force said he had no immediate information on the reports. British media earlier reported that RAF planes had approached Russian bombers on Tuesday as they headed toward British air space.
Britain on Monday ordered four diplomats to leave as punishment for Russia's refusal to extradite the man named by Britain as the chief suspect in last year's killing in London of ex-Russian security officer-turned-Kremlin critic Alexander Litvinenko.
Russia on Thursday ordered four British diplomats to leave in a reciprocal move.
That response appeared to indicate that neither side wished to escalate the tensions further. Russian President Vladimir Putin on Thursday expressed confidence the nations would overcome their differences.