There is “no blank cheque” for the UK’s nuclear deterrent, Commons Leader Penny Mordaunt has said.

She was speaking in the Commons after SNP MP Patricia Gibson questioned whether the programme should continue given wider cost pressures.

The SNP does not support the retention or renewal of the Trident deterrence system, which is operated from HM Naval Base Clyde in Scotland.

A programme to replace the submarines used for the continuous-at-sea Trident deterrence system is currently under way.

There is no blank cheque for the nuclear deterrent. But it is there dong a vitally important job.

Ms Gibson (North Ayrshire and Arran) said: “For the first time since 1961 UK Government debt has risen above 100% of GDP, with the Office for National Statistics revealing that net debt reached £2.6 trillion as of the end of May.”

She asked the Commons Leader whether she believes “a blank cheque for replacing Trident is either acceptable or sustainable” given “the huge pressure on public finances”.

Ms Mordaunt said: “I don’t think this Government should take any lessons from the SNP Government that has nearly £2 billion between what it spends and what is in its budget.

“In addition to understanding cost and the price of everything, I think it is also important that (we) in this place understand the value of things.”

She added: “There is no blank cheque for the nuclear deterrent. But it is there doing a vitally important job.

“If (MPs) can’t see the merits of us having a deterrent, at this moment, I don’t know that they are ever going to be able to grasp this.

“Commitments to having a nuclear deterrent are pretty fundamental to being a member of Nato,” she added.

The cost of maintaining the nuclear deterrent is estimated at £3 billion for this year, with between £31 billion and £41 billion set aside for the wider programme of replacing the Vanguard-class submarines with new Dreadnought submarines, according to figures from the House of Commons Library.