Aircraft based at an RAF base are conducting "activity" off Scotland in response to reports a Russian submarine has been seen nearby, the British ministry of defence has confirmed.

It is understood that a navy frigate and a submarine are also involved in the hunt.

It comes days after RAF Typhoons were forced to intercept Russian Tu-160 Blackjack aircraft that strayed into the vicinity of UK airspace.

The Sun on Sunday reported that a French patrol aircraft was carrying out the search as the UK no longer has any specialist sub-hunting aircraft.

Britain scrapped their airforce's Nimrods with search capability in 2010 after a review.

The Telegraph reported that two French Atlantique 2 maritime patrol planes and a Canadian plane were now operating out of RAF Lossiemouth, about 60km east of the Scottish city of Inverness.

The defence ministry admitted that allied planes were operating from the base but refused to comment on naval manoeuvres.

"We can confirm that allied maritime patrol aircraft based at RAF Lossiemouth for a limited period are conducting activity with the Royal Navy," a statement said.

"We do not discuss the detail of maritime operations."

The search comes as David Cameron is due to announce a large investment in resources for the military, which has undergone several years of cuts.

One of the commitments is to buy nine Boeing P8 Poseidon maritime patrol aircraft which will be capable of hunting submarines.

Last year, British authorities faced embarrassment when it emerged it had to seek the help of the US, France and Canada when trying to find another Russian submarine spotted off the west coast of Scotland.

At that time it was thought the Russian vessel was possibly tracking UK nuclear submarine movements from the Clyde.