Britain summoned Russia's ambassador Thursday and asked him to explain why Russian warplanes flew near British airspace, disrupting civil aviation.

The Foreign Office said Thursday that Royal Air Force Typhoon jets were scrambled to escort Russian Bear bombers in a "U.K. area of interest" on Wednesday. The Russian planes did not enter British airspace, but flew along the coast and over the English Channel without communicating with British air traffic control.

The Foreign Office called the manoeuvres "part of an increasing pattern of out-of-area operations by Russian aircraft" and said the ambassador had been summoned to account for the incident.

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Tensions between Russia and NATO nations have been high amid fighting between Ukrainian government troops and Russia-backed rebels in eastern Ukraine.

NATO said its pilots conducted more than three times as many intercepts of Russian planes in 2014 as the year before.

Britain's Ministry of Defence said it intercepts Russian planes about once a month.