Two Russian Bear long-range bombers, which were intercepted by British Typhoon fighter jets while flying near the U.K.'s southern coast on Wednesday, caused disruptions to civil aviation, Britain’s Foreign and Commonwealth Office said Thursday.

According to U.K. officials, the Russian planes did not trespass on British airspace but their movements were part of an "increasing pattern of out-of-area operations” by the Russian government. The Russian bombers, which are capable of carrying nuclear missiles, were escorted by Royal Air Force (RAF) jets “throughout the time they were in the UK area of interest,” BBC reported.

While the Foreign Office did not provide details of the disruption to civil aviation caused by the two Tu-95 Bear H bombers, BBC reported that the planes came within 25 miles of the U.K. border. The bombers did not file flight plans with the local civil aviation authority and they were not communicating with air traffic control, BBC reported, adding that the Russian planes did not have their transponders on.

On Thursday, the Foreign Office also summoned Russia's ambassador Alexander Yakovenko to “account for the incident.” The Russian envoy said that the British authorities' concerns were not reasonable as the Russian military planes were on a routine air patrol over the Atlantic Ocean, RIA Novosti reported.

According to Yakovenko, the bombers' flight complied with international regulations, and so could not be considered threatening or disruptive. A Russian Air Force spokesman reportedly said Thursday that the military planes had expected to be escorted by RAF Typhoon aircraft, Norwegian F-16s and French Mirage fighters at different stages on their planned 19-hour flight route over the North Atlantic.