London: Britain said on Wednesday it had scrambled Typhoon fighter jets to intercept seven Russian military aircraft flying near the Baltic states, as tensions between the West and Russia over Ukraine remained high.

A NATO official said the Russian aircraft were armed and in the vicinity of NATO airspace.

They did not file a flight plan and did not use their transponders, making them invisible to civilian air traffic control and a safety hazard to commercial air traffic, which was why NATO had intercepted them, he said.

The alliance last month tripled the number of fighter jets based in the Baltics as part of measures to beef up its defences in eastern Europe following Russia's annexation of Crimea. Britain contributed four Typhoons to the operation.