Peterson Air Force Base, Colorado - US and Canadian warplanes intercepted two Russian and two Chinese bombers in international airspace near Alaska on Wednesday, the joint US-Canadian North American Aerospace Defense Command (NORAD) said.

"NORAD detected, tracked, and intercepted two Russian TU-95 and two PRC H-6 military aircraft operating in the Alaska Air Defense Identification Zone," the statement said.

The zone is a perimeter in which air traffic is monitored beyond the border of national airspace to provide extra reaction time in case of hostile actions.

Intercepts of Russian aircraft – which amounts to American or Canadian planes contacting them visually or electronically – are relatively common in the area.

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"Fighter jets from the United States and Canada conducted the intercept," NORAD said, adding that the bombers "remained in international airspace and did not enter American or Canadian sovereign airspace," and that their activity "is not seen as a threat."

Amid soaring tensions between the US and Russia over Moscow's invasion of Ukraine, however, such incidents have led to increased concerns over the possibility of a direct confrontation.

On Sunday, Russian fighter jets were scrambled in an effort to prevent two US strategic bomber planes from potentially crossing the Russian border over the Barents Sea in the Arctic.

Washington insisted that bombers were conducting routine flights in neutral airspace and in accordance with international law.