A £5.5 billion light tank programme beset by problems with noise and vibration may have to be abandoned, the Government admitted.

Defence Procurement Minister Jeremy Quin insisted the military, officials and contractor General Dynamics were all committed to making the Ajax vehicle a success.

But he told MPs “we can’t be 100% certain that can be achieved” and military commanders are already working on contingency plans in case the armoured vehicles cannot be used.

Trials of the light tank have been paused because of safety concerns which have left some personnel complaining of vibration injuries while others have suffered hearing loss – in some cases requiring steroid treatment in an attempt to reverse the damage.

Mr Quin told the Defence Select Committee: “I have described Ajax as a troubled programme, I wish it wasn’t, but it is.

“It requires a lot of work from ourselves and our industry partners to get ourselves back on track.

“We can’t be 100% certain that that can be achieved.

“But this programme matters to the British Army, to 4,100 employees in 230 companies across the UK, and we will do our utmost to succeed.”

The overall cost of the contract is £5.5 billion, with around £3.2 billion of taxpayers’ money spent so far.

A new official will be appointed to oversee the programme until it reaches final operational capability (FOC) – or is scrapped.

“We are currently undertaking a search for the right person who will be responsible for the delivery of this programme through to FOC or indeed informing ministers if – which we sincerely hope is not the case – this is for any reason unachievable,” Mr Quin said.

Tory committee member Mark Francois, a former defence minister, said: “If you are having to give people steroid injections after having been in the vehicle, that tells you everything you need to know.”

It was time to “rip the plaster off” and cancel it, he said.

Committee chairman Tobias Ellwood welcomed the minister’s “willingness to conduct a review and make a sober assessment as to whether you can genuinely go forward with this or whether it is then time to draw a line”.