An independence referendum held without the permission of Westminster would be illegal, Scottish Secretary Alister Jack has said.

The SNP released an 11-point plan last week stating they would hold another vote if a pro-independence majority of MSPs was returned in May’s Holyrood elections, whether a Section 30 order granting it from London was forthcoming or not.

The document, put together by Holyrood Constitution Secretary Mike Russell, would effectively dare the UK Government to challenge another referendum in court.

However, Mr Jack told the BBC another vote without express permission would be illegal.

He said: “I’m afraid the constitution is a reserved matter, it would be an illegal referendum, let’s be clear about that.”

We can't go into a process of 'neverendums' until eventually they get one that they win, that's not what responsible government is about

The Scottish Secretary said it was “not the time” for another vote on the constitution in Scotland, reiterating that senior figures in the Yes campaign and its own white paper said the vote was “once in a generation”.

He added: “We can’t go into a process of ‘neverendums’ until eventually they get one that they win, that’s not what responsible government is about.

“We had a referendum in 2014, we’re now in a global pandemic, we’re going to have double-dip recession the way things are going.

“It’s about recovering our economy as one United Kingdom, pulling together, doing the trade deals we want to do, improving Scotland’s economy and rebuilding it as quickly as we can, and after we’ve saved people’s lives with this vaccine, then saving their livelihoods.”

SNP depute leader Keith Brown said: “The Tories sound more rattled by the day and it’s clear they are completely out of ideas and excuses.

“Trying to block a democratic mandate is an indefensible and untenable position – the bottom line is the Tories are panicking as they run scared of a referendum they fear they will lose.

“It’s not for Alister Jack, or his boss Boris Johnson, to deny the people of Scotland the chance to determine their own future. That choice belongs to the people of Scotland and any Trump-like attempt to deny that would be utterly undemocratic – and would not hold.”

Mr Jack’s comments come just days after the Prime Minister touted the strength of the Union on a visit to Scotland.

When asked about the visit, Mr Jack said it was essential, adding it was “morale boosting”.

“In any battle, the general should go to the front line and hear from those people, those troops – who are fighting in this case the virus – exactly the issues they’re facing,” he said.

“It’s morale boosting what he does, he thanked the troops who were rolling out the vaccine centres … it’s important to talk to people, to thank them, to hear what issues they’re facing.”

Mr Jack also said he does not believe the Scottish Government should publish future vaccine supply data.

The UK Government previously rebuked the devolved administration for publishing such data earlier this month, claiming it could be commercially sensitive.

The Scottish Government has now pledged to publish historic vaccine figures, such as how many doses were promised and how many were delivered, from next week.

“I said this to the First Minister in a phone call last night, I think the number that should be published is the historical data of what’s available to the Scottish Government, which will be north of one million.”

He said this week there will be around 1.15 million doses of the vaccine in Scotland while only 551,008 have been injected so far.

Mr Jack claims the vaccine is held in a central site for the whole of the UK, with doses delivered the next day at the request of the Scottish Government.