Britain has summoned Russia's ambassador to explain why two Russian bombers flew over the English Channel, forcing civilian aircraft to be diverted.

British Typhoon fighter jets were scrambled on Wednesday when two Russian TU-95 'Bear' long-range bombers flew near UK airspace.

A British Foreign Office spokesperson said while the planes stopped short of entering British airspace, the incident was part of an "increasing pattern of out of area operations by Russian aircraft".

A spokesperson said: "While the Russian planes did not enter sovereign UK airspace and were escorted by RAF Typhoons throughout the time they were in the UK area of interest, the Russian planes caused disruption to civil aviation.

"That is why we summoned the Russian Ambassador today to account for the incident."

The Royal Air Force said in a statement that Typhoon fighters were scrambled from RAF Lossiemouth and RAF Coningsby.

They monitored the Russian planes for more than 12 hours, until "they were out of the UK Flight Information Region".

A British government source told Reuters the Russian move was viewed as "a significant escalation".

"It was very dangerous. Civil aircraft flying to the UK had to be re-routed," the source said.

"The Russians were flying with their transponders turned off so could only be seen on military radar.

"They haven't flown this far south before."

Typhoon fighter jets were scrambled on 29 October and 1 November to intercept Russian aircraft which approached UK airspace.

Analysts said at the time the incidents appeared to be a "show of force" by President Vladimir Putin.