A TREASURY-enforced shake-up of Britain's air defence will lead to more aircraft being based at North Yorkshire's front-line fighter base RAF Leeming.

But fears that the move could leave London wide open to a September 11-style attack have been dismissed by the Ministry of Defence.

The Royal Air Force announced yesterday that it is to axe the Tornado F3-equipped No 5 Squadron, based at Coningsby in Lincolnshire, from next summer.

The permanent disbandment comes amid a Treasury squeeze on the cost of running the armed forces and will see the number of F3-flying air defence squadrons reduced to four.

Two of those squadrons, numbers XI and 25, are based at Leeming, near Bedale, while the remaining two are at Leuchars in Scotland. Crew and aircraft of the axed unit will be distributed among them.

Major works are now to be carried out to strengthen the runway at Coningsby prior to the arrival of the new Eurofighters, possibly towards the end of 2004.

However, the station is the closest air defence base to London, leading to fears that the capital is losing a vital protection force.

Shadow defence secretary Bernard Jenkin said: "No 5 Squadron has been on standby to protect London from a Twin Towers-type attack since September 11. There can be no rational strategic or military reason for this."

The F3 variant of the Tornado is the RAF's main fighter-interceptor and while Leeming is the next closest F3 base to the capital, it is still nearly twice as far away as Coningsby.

However, the MoD insists the move will not affect the RAF's ability to defend London from the air.

"The F3s provide the standby, quick-reaction alert aircraft and there will always be one or two of the aircraft based in Lincolnshire or points south," said a spokesman yesterday.

The specified aircraft, whose crews are on a Battle of Britain-style constant alert, are deployed to various bases, which are not disclosed for security reasons.

"Just because their home bases will be further north does not mean they will be there all the time," said the spokesman.

"We will use somewhere suitable to provide cover for the south of England and there will be no diminishing of the effectiveness of our air defences.