Russian military aircraft posing threat by turning off communication devices

Russian military aircraft are posing a threat to civilian planes by turning off communications devices and failing to file flight plans, the US ambassador to Nato said.

Russia has stepped up flights near Nato's borders last year, the alliance says, coinciding with increased East-West tension over Russia's role in the Ukraine crisis. Nato aircraft have scrambled more than 400 times this year to intercept Russian aircraft, up 50 per cent from the 2013 total.

US Ambassador Douglas Lute said on Monday there had been "multiple incidents" where Russian military aircraft had not filed flight plans or spoken to civilian air traffic controllers and had turned off transponders that send information about the plane.

This made the planes virtually invisible to air traffic controllers, he said during a news conference. "These Russian actions are irresponsible, pose a threat to civilian aviation and demonstrate that Russia is flagrantly violating international norms," he said.

Nato's secretary general, Jens Stoltenberg, urged Russia to conduct the flights "in a more responsible way". Britain also voiced concern about Russian probing of its air space.

In late October, Nato said its aircraft tracked Russian strategic bombers over the Atlantic and Black Sea and sorties of fighters over the Baltic.