SNP MPs will vote against Boris Johnson’s Brexit deal when it comes before the Commons, Westminster leader Ian Blackford revealed as he branded it a “disaster for Scotland”.

He said the agreement, which was finally reached with the European Union on December 24, was an “unforgiveable act of economic vandalism and gross stupidity”.

SNP leader and Scotland’s First Minister Nicola Sturgeon has already accused the Conservatives of having “sold out Scottish fishing all over again” in the Brexit treaty.

But Alister Jack, the Scottish Secretary, insisted it would deliver for all parts of the UK, as he urged all MPs from north of the border to “give it their wholehearted support”.

Mr Jack made the plea after the SNP Westminster leader said the agreement – which was published in full on Boxing Day – was a “very bad deal for Scotland”.

It will come into force after the UK’s current transition period, as it exits the EU, comes to an end on December 31.

MPs in the House of Commons will vote on the agreement on Wednesday December 30, with Mr Blackford saying: “Boris Johnson’s extreme Tory Brexit is an unforgivable act of economic vandalism and gross stupidity, which will cause lasting damage to the economy and leave the UK much worse off at the worst possible time – during a pandemic and economic recession.”

The Scottish Government has estimated the Brexit deal that has been agreed could cost Scotland’s economy more than £9 billion by 2030, compared to staying in the EU, with the forecast 6.1% drop in GDP the equivalent to losing the equivalent of £1,600 per person.

Mr Blackford hit out: “Scotland has been completely ignored by Westminster throughout the Brexit process and we are being forced to pay a devastating price.

“It is clear that the only way to protect Scotland’s interests, and regain the full benefits of EU membership, is to become an independent country.

“This is a very bad deal for Scotland, which will terminate our membership of the EU, rip us out of the world’s largest single market and customs union, end our freedom of movement rights, and impose mountains of red tape, added costs and barriers to trade for Scottish businesses.

“The blame lies squarely with the Tory government.”

Mr Blackford continued: “Industries and communities across Scotland will face higher costs and reduced access to EU markets.

“Benefits of EU membership, including our right to live, work and study across Europe will be stripped away. Justice and security cooperation will be diminished. Even the broken promises made to our fishing communities have turned out to be another Tory pack of lies.

“With the Labour Party lining up behind Boris Johnson, it is clear Westminster will impose this hard Tory Brexit regardless of how Scotland votes but it is not being done in our name. It is a disaster for Scotland.”

But Mr Jack insisted Scots would expect their MPs to “do the right thing” and back the agreement in Wednesday’s Commons vote.

The UK Government minister said: “We have secured a historic Free Trade deal with the EU that delivers for Scotland and the whole of the UK.

“This is a deep and wide-ranging deal, covering trade, security, travel, transport, energy, health and social security.

“As Parliament prepares to vote on the deal this week, I urge all Scottish MPs to give it their wholehearted support.”

Mr Jack continued: “Outside the EU, the UK can sign our own trade deals around the world, bringing new opportunities for exporters and some of Scotland’ most iconic products.

“For our farmers, the deal avoids tariffs on their world-beating Scotch lamb and beef.

“For our fishermen and coastal communities, the deal delivers what we promised. We are regaining control of our waters, we are restoring our status as an independent coastal state and, even during the five-year adjustment period, there will be a big overall increase in our share of the catch in our waters.

“As we leave the Common Fisheries Policy, our fishermen will also enjoy near-exclusive access to inshore waters up to the historic 12-mile limit.”

The Scottish Secretary insisted: “The deal is good news for Scotland and I believe it is now time to move on from the Brexit debate and join forces in embracing our exciting future.

“Whether Leaver or Remainer in 2016 we need to come to together to make the most of our new opportunities. The people of Scotland will expect their MPs to do the right thing on Wednesday and vote for the deal.

“They will not easily forgive those who reject this Free Trade Agreement or throw their weight behind a no-deal Brexit.”