Doubts over the Government's plan to order two 65,000-tonne aircraft carriers were lifted yesterday when the Ministry of Defence announced that it was ready to sign the £3.9 billion contract. A full audit of the carrier programme, including an assessment of whether there will be enough crew and pilots to man the huge vessels, has been ordered by one of the MoD's senior military commanders.

The breakthrough in the long-awaited contract came yesterday when Des Browne, the Defence Secretary, gave approval for building the two super-carriers, the first of which, HMS Queen Elizabeth, is supposed to be ready for operations in 2014.

The confirmation from Mr Browne means that two of the principal firms involved in the contract — BAE Systems and the Vosper Thornycroft (VT) Group — will be able to press ahead with forming a joint venture company that will build and assemble the carriers at shipyards in Portsmouth, Barrow-in-Furness, Glasgow and Rosyth.

Once the two firms have forged the new company and sought approval from shareholders, the MoD will sign the contract. Defence sources said that this was expected by mid-June.

The audit of all the implications for operating a carrier-strike capability on such a grand scale was ordered by General Sir Timothy Granville-Chapman, the Vice-Chief of the Defence Staff, on behalf of the Service chiefs. As reported in The Times on Saturday, he wrote to all one-star and two-star officers at the MoD this month, asking for their views on every aspect of the vessels.

Critics have expressed concern that the Navy will not have sufficient manpower to run two such huge carriers, let alone the pilots to crew the 40 aircraft with which each ship will be armed — 36 joint strike fighters and four early-warning aircraft.

Defence sources said that the review was being conducted by the Directorate of Operational Capability, a small tri-Service organisation, headed by Air Commodore Mark Swan, which would be expected to report back within three or four months.

The directorate will examine the present carrier strike capability and review what will be required for the new ships. Apart from manpower, the carriers will need escort ships, refuelling tankers and other support vessels, the sources said.

However, the Defence Secretary's announcement was an indication that the MoD has completed all the necessary financial, commercial and management arrangements for the programme.

The MoD said “written assurance” had been given to industry “that we are ready to sign contracts as soon as the new shipbuilding joint venture ... has been formed”.

The programme is expected to generate 10,000 jobs at the peak of production. Other members of the shipbuilding alliance that will make the carriers include Babcock and Thales UK.

The cost has already risen hugely. The original estimate for two 40,000-tonne ships was less than £1billion. When they were increased to 65,000 tonnes, the MoD's estimate was £2.9 billion, but industry said ships of this scale could not be built for less than about £4 billion. The carriers are to be 280m long and 70m wide.

Mike Turner, chief executive of BAE Systems, said: “This is an important milestone in the development of the carrier programme and plays a major part in the long-term sustainability of the UK naval sector and the transformation of our business.”

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