The Ministry of Defence has been condemned for the “severe mismanagement” of nuclear programmes after a "disturbing" report revealed systematic failings.

The National Audit Office (NAO) report found that the MoD’s management of three nuclear-regulated sites “contributed to a combined cost increase of £1.35 billion and delays of between 1.7 and 6.3 years”.

The report also found the network of equipment, people, and infrastructure required to maintain the Trident nuclear system would cost a further £2.5bn.

It comes after a Freedom of Information request showed that there had been 40 safety lapses on nuclear convoys in the three years since 2016. Convoys carrying nuclear bombs and radioactive materials have been stopped by everything from faulty windscreen wipers to brake trouble, the request revealed.

READ MORE: MoD: 40 nuclear lapses in three years ‘show how safe Scotland is’

Commenting on the NAO report, the SNP's shadow defence secretary Stewart McDonald said: “This extremely disturbing report not only highlights a worrying trend of severe mismanagement by the MoD both in its administration and its finance, but it also shines a light on the soaring cost of maintaining weapons of mass destruction.

“This latest National Audit Office report comes off the back of a Freedom of Information request that revealed that there were a staggering 40 safety lapses for convoys carrying nuclear weapons and radioactive materials.”

The NAO report said MoD failures to learn from past mistakes meant key projects to upgrade the Defence Nuclear Enterprise were over-budget and behind schedule.

It said "inappropriate" contracts with outside contractors and beginning building work on facilities before the designs were "sufficiently mature" had added hundreds of millions of pounds to costs.

And it highlighted a lack of technical skills within the MoD which resulted in the "gold-plating" of designs as staff were unable to challenge regulators when they insisted upon overly-complex specifications.

McDonald added: “Communities will be rightly concerned that Scotland’s roads are regularly being used by military convoys with nuclear warheads on board – but they will no doubt be shocked that safety lapses are so common and unaddressed.

“The Tories have spent vast sums on nuclear weapons all the while neglecting and under-resourcing serious security priorities such as cybersecurity.

“Under this Tory government the management of the MoD to date has been shambolic, with the NAO previously concluding that the military’s previous two Equipment Plans were deemed simply ‘unaffordable’ two years in a row with a black hole of up to £15 bn."