SCOTLAND’S First Minister has challenged Theresa May to come clean with a full disclosure as to whether she knew about a reported misfire of the UK’s nuclear weapons system before a crucial Commons vote to spend £40 billion renewing Trident.

Nicola Sturgeon, who has described the nuclear weapons system as “immoral” and impractical”, tweeted: “This is a hugely serious issue. There should be full disclosure of what happened, who knew what/when, and why the House of Commons wasn’t told.”

SNP MPs are also demanding to know if the Prime Minister was part of an alleged “cover-up” over a failed test of the Trident nuclear deterrent after she failed to answer four direct questions on her knowledge of the test, which reportedly took place weeks before MPs approved the renewal programme in July.

Reports claim that the launch of an unarmed Trident II D5 missile from a British submarine off the coast of Florida in June malfunctioned but May did not mention this test in a speech to MPs before the Commons vote, in which she urged them to back renewal, leading to allegations the said malfunction has been covered up. Labour leader Jeremy Corbyn called the failed test “a pretty catastrophic error” and Labour peer and former senior Royal Navy officer Admiral Lord West added it was “bizarre and stupid” to not tell anyone about the test.

When May appeared on the Andrew Marr BBC show yesterday, she said she had “absolute faith” in the Trident missiles but repeatedly failed to address whether she knew about the alleged failed test before her speech to MPs.

She said: “When I made that speech in the House of Commons, what we were talking about was whether or not we should renew our Trident, whether or not we should have Trident missiles, an independent nuclear deterrent in the future. I think we should defend our country, I think we should play our role in Nato with an independent nuclear deterrent. Jeremy Corbyn thinks differently, Jeremy Corbyn thinks we shouldn’t defend our country.” She gave similar answers to further questions on the subject.

SNP Westminster leader Angus Robertson called on May to personally come to parliament this week and tell MPs exactly what and when she knew about the alleged Trident missile launch malfunction.

Robertson said: “The Prime Minister must come to Parliament this week and outline exactly what she knew – and when – about this reported malfunction and alleged UK Government cover up. It would be utterly unacceptable, and deeply serious, if it turns out that this information was deliberately kept from MPs at the time of the renewal vote for the Trident weapons of mass destruction programme.

“Parliament and the public have a right to know if these reports are true, and there must be full disclosure about what happened, who knew, when they knew, and why the House of Commons wasn’t informed. The Prime Minister cannot continue to dodge the question.”

In July, 58 of Scotland’s 59 MPs voted against renewal and SNP defence spokesperson Brendan O’Hara MP said that if May is guilty of a cover-up, it would be a “sickening betrayal”.

He added: ‘’Trident is obscenely expensive and morally repugnant. If we now have to add that there is a real possibility it is unreliable and unsafe – then there must be massive question marks about its viability. If it turns out the UK government covered up these safety concerns just before Westminster voted to renew – that would be a sickening betrayal.”

A UK Government spokesman described the capability and effectiveness of the Trident missile as “unquestionable” and said there had been a routine unarmed Trident missile test launch from HMS Vengeance in June to certify the submarine.

“Vengeance and her crew were successfully tested and certified, allowing Vengeance to return into service. We have absolute confidence in our independent nuclear deterrent.

“We do not provide further details on submarine operations for obvious national security reasons,” he added.