EXCLUSIVE

FEARS are growing among senior Royal Navy officers that the Government is trying to renege on its promise to build and equip two large aircraft carriers designed to project British military power worldwide by 2012.

Despite Defence Ministry claims that the project has priority in its ''smart procurement'' initiative, the Treasury is understood to be demanding a cheaper, stopgap alternative, based on extending the life of the three small existing and rapidly ageing carriers for an extra decade, be implemented instead.

Treasury officials are horrified by the estimated #9.4bn bill for 40,000-tonne ships and high-performance aircraft needed to fulfil Labour's pledge in the July Strategic Defence Review. The cost of aircraft alone would top #7bn, according to an MoD memo, and could escalate beyond that.

UK shipyards including Babcock Rosyth in Fife, Harland and Wolff in Belfast and Cammell Laird at Birkenhead are to be invited to submit tenders for a study into the cost of patching up the three 19,000-tonne mini-carriers - Ark Royal, Illustrious and Invincible - to stave off the worst ravages of time and keep at least two of them seaworthy at any time.

The oldest of these ships, built as anti-submarine helicopter platforms for Cold War service, was commissioned in 1980 and would be 32 years old - older than most its crew - by the proposed date for the introduction of modern replacements. The last of the three entered service in 1985.

The regular aircraft complement of each ship is eight Sea Harrier fighter-bombers and up to 11 Sea King helicopters. A handful of extra Harriers can be squeezed on in an emergency.

The average American carrier weighs in at about 100,000 tonnes and has an aerial strike force of 50 aircraft. Each is a floating town with a crew of 5000-6000 and can dominate and control an area stretching 500 miles from the ship in every direction.

Two of the British carriers took part in the Falklands campaign, where their lack of embarked air power meant inadequate fighter cover over the beach-heads and inevitably resulted in casualties among the naval and support vessels supporting the landings.

The new carriers were to be the centrepiece of the new UK strategy of intervention worldwide in support of United Nations or Nato missions. Their advantage is the use of floating airfields without the political problem of persuading allies to provide land bases.

The preferred military option for new aircraft was a stake in the US Joint Maritime Strike Fighter programme, still in its planning and development phase. The MoD, while expressing an interest in the plane, is also looking at converting some of the RAF's 232 ordered Eurofighters for naval use to save money.

Mr John Spellar, Defence Minister, said yesterday that the two proposed carriers were still a priority, but insisted that cost-savings of #2bn over the next decade were a key element in ensuring that new equipment would be purchased.

A Navy insider said later: ''There are growing doubts about MoD resolve in the face of Treasury interference. We will probably end up with a compromise which falls far short of the strategic aim of the exercise and leaves us with second-rate ships and aircraft.

''The three anti-submarine warfare carriers are carrying out tasks for which they were not designed. Their obsolescence and lack of striking power are already apparent. By 2022, they will be antiques incapable of global power projection.''