By politics.co.uk staff
Britain's two new aircraft carriers could cost up to £2 billion more than initially planned.
The original £5.2 billion deal the Ministry of Defence (MoD) has agreed with defence firms constructing the carriers now appears unlikely to become reality, the BBC reported.
Instead the cost is set to creep up to as much as £7 billion, according to Thales, BAE Systems and Babcock.
Shadow defence secretary Jim Murphy said he feared the aircraft carriers could turn into a "£2 billion bungle".
"The government has totally mishandled the UK's carrier capability and now needs to be totally clear about whether both carriers will be completed and capable of deployment," he added.
"The strategic defence and security review (SDSR) is unravelling and ministers must give the country confidence that they have a grip of the budget and equipment programme."
HMS Prince of Wales and HMS Queen Elizabeth were saved from spending cuts in the SDSR because too much had already been spent to justify their cancellation.
One carrier, HMS Prince of Wales, is to be placed into 'extended readiness' on completion - meaning it will be mothballed.
Britain has agreed a reciprocal arrangement with France which will see it share HMS Queen Elizabeth with the French Navy's carrier Charles De Gaulle when its own carrier is in dock for maintenance work.
Under plans agreed in the SDSR, HMS Queen Elizabeth will be fitted with catapults and traps allowing it to operate the carrier variant of the joint strike fighter.
The MoD said this aircraft carried a greater payload, has a longer range and is cheaper to purchase.
"This will give our new carriers, which will be in service for 50 years, greater capability and interoperability with our allies," a spokesperson said.
"Final costs are yet to be agreed and detailed work is ongoing. We expect to take firm decisions in late 2012."