( Sky ) - The Bear Tu95 planes - which can carry nuclear and Cruise missiles - were detected by Nato early this morning.
Tornado intercepts Bear last monthBritish fighters were scrambled from RAF Leeming in Yorkshire and the Russian planes diverted before entering British territory.
They and headed back to their base in north Russia without incident and are still thought to be in the air, with Nato tracking their progress.
Sky's Defence Correspondent Geoff Meade said: "Diplomatic relations between Moscow and London haven't been great for some time and I think this is maybe a bit of sabre-rattling on behalf of the Russians.
"This is the biggest formation of Russian aircraft to be challenged in this way since the Cold War and marks a stepping up of Moscow's challenge to British defences."
He described the incident - the second of its kind in a month - as a "probing mission".