THE UK Government has been condemned for the "chaos" surrounding its decision to switch the type of jets to be used on the Royal Navy's new aircraft carriers, which will cost tax-payers at least £100 million.

In the 2010 defence review, the Coalition announced it would adopt the carrier variant of the US-built F35 Joint Strike Fighter rather than the "jump jet" version chosen by the previous Labour Government.

Ministers argued the so-called "cat and trap" variant was a more capable aircraft, which would increase "inter-operability" with other navies, even though it meant mothballing one of the two carriers on grounds of affordability.

However, Defence Secretary Philip Hammond announced in May the Ministry of Defence (MoD) was reverting to the jump jet version amid fears the costs of fitting the catapults and arrestor gear – the "cats and traps" – were spiralling out of control.

In a critical report, the House of Commons Defence Committee said the 2010 decision to go for the carrier variant was a mistake, which led to increased costs and further delays to the carrier programme.

The report stated: "It is clear the decision was rushed and based on incomplete and inaccurate policy development. It was taken without the MoD understanding how the change could be implemented. Perhaps the primary example of how little the MoD understood about this decision is the fact it was supposed to improve inter- operability. This turned out to be incorrect."

The committee complained that the lack of a proper defence industrial strategy put the UK at a disadvantage compared with competitor countries.

It said: "We do not understand how we can have confidence in a national security strategy which does not show a clear grasp of what is needed for the defence of the United Kingdom.

"The overriding reason for the purchase of any item of defence equipment must be its quality and the requirements of the armed forces. We consider nonetheless the Government should take into account, in buying equipment, the enhanced opportunities for export of equipment in use by UK armed forces."

Philip Dunne, the Defence Procurement Minister, said the MoD's newly published 10-year equipment plan would ensure the armed forces received the hardware they needed.

He added: "The increased financial contingency will help cover future risk and make our equipment programme afford-able. There is also greater information for industry about our priorities, helping them to invest in the future capabilities our troops need."

He insisted the switch to the carrier variant of the F35 had been "right at the time" but that "unacceptable cost growth, technical risk and project delays" meant the decision to revert to the jump jet was "in the best interest of defence".

Jim Murphy, the Shadow Defence Secretary, said the committee's report was another blow to the country's confidence in the Government's competence on defence and would cost taxpayers at least £100m.

He added: "Days after the confusion and contradiction on defence spending, the chaos of the aircraft carrier decision is laid bare. This wasted time and money and led to a serious capability gap."

Mr Murphy called for a new industrial strategy to "improve the speed of procurement, share the burden of risk with industry, support small businesses and strengthen collaboration between companies, the MoD and the military".

Labour's Thomas Docherty who sits on the committee, told The Herald: "Scotland came within a hair's breadth of losing work on the second aircraft carrier, which would have had a devastating impact on the Clyde and Rosyth. This fiasco led to a £100m loss to the taxpayer."