(CNN) The UK Royal Air Force on Tuesday scrambled Typhoon jets to intercept Russian bombers flying near British airspace, the British Defence Ministry said.

Further details about the incident weren't immediately available. It is one of the latest incidents in what NATO has said is an increase in Russian military flights near alliance members' territory.

In November, NATO said its members' jets had been scrambled more than 400 times in 2014 to intercept Russian military flights close to members' territories -- a 50% increase over the previous year. The increase harks back to the days of the Cold War, NATO Secretary General Jens Stoltenberg said November 20 during a visit to NATO member Estonia.

"This pattern is risky and unjustified," Stoltenberg said. "So NATO remains vigilant. We are here. And we are ready to defend all allies against any threat."

In a November report, the European Leadership Network listed more than 40 "close military encounters between Russia and the West" in the eight months from March to October.