A billion-pound upgrade to the Royal Air Force's Tornado bomber plane has left the aircraft unable to fire its precision missiles, the BBC has learned.

The new Tornado GR4 cannot deliver the smart bombs, which are central to the way modern air wars are fought.

The bomber's laser targeting device does not work on the upgraded aircraft.

An unnamed RAF officer from a squadron using the upgraded Tornadoes told the BBC: "We're spending £1bn and we have ended up with an aircraft that is less capable than when we started."

British Aerospace is the company carrying out the upgrade. There are currently about 50 upgraded GR4s are in service with frontline squadrons, but the MoD has admitted no Tornado GR4s are "cleared for full operational service".

"The GR4 will be fully operational by late 2000," the MoD said in a statement to the BBC.

But a BBC correspondent says that date will be two years after the GR4 was delivered to its first front line squadron.

Seven times less money

The BBC has also learned that the man chosen to sort out the Tornado upgrade, Air Commodore Alistair Lang, was moved from his post before he had even started work.

Air Commodore Lang managed a similar upgrade of another RAF bomber, the Jaguar.

The upgrade was carried out by the RAF and came in on time, on budget and for seven times less money per aircraft than the GR4.

Air Commodore Lang was not available for comment but the BBC understands he was moved after saying he wanted to try something similar with the Tornado.

The MOD described the decision as an internal management matter.

Aviation writer Bill Gunston, a former technical editor of Flight Magazine, was very criticial of the way the upgrade had been handled.

"We seem to have a genius for doing things in a bad way," he said.

"The Tornado GR4 has a long way to go before, in my opinion, it is fit to carry the banner of the Royal Airforce into the front line."

He said Air Commodore Lang had a "brilliant reputation" and that his removal has made the Tornado community "desperately upset".

However Bruce George, chairman of the House of Commons Defence Committee, said the unreadiness of the GR4s was not a serious procurement failure.

He said the National Audit Office's view was the upgrade project, started in 1993-94, was "proceeding to time and cost in line with the latest project approval".

"I'm not happy with what has happened but it does not come on to the Defence Committee's at-risk list," he added.