Two RAF Typhoons have been scrambled from a Romanian air base to engage Russian drones close to Nato airspace, although they did not open fire.

British defence sources said the fighter jets did not enter Ukrainian airspace, contradicting reports that Russian drones had been shot down by the RAF there, an event which would have represented a major escalation in hostilities between the western alliance and Moscow.

Romanian officials reported that the Typhoons took off at 2am on Saturday in response to the drone threat, established radar contact on the targets and had authorisation to engage if necessary.

A shooting down of Russian drones inside Ukraine would be significant because it is not a member of Nato and the west has consistently refused to police its skies to avoid a direct confrontation with Russia.