THE SNP leadership today urges its Westminster rivals to put party politics aside and unite at a New Year summit to see off a “catastrophic” hard Brexit, which it warns would threaten Northern Ireland’s peace process.

Ian Blackford, the Nationalist leader at Westminster, has written to senior party leaders – including Labour’s Jeremy Corbyn and the Liberal Democrats’ Sir Vince Cable – inviting them to a cross-party summit to protect the UK’s membership of the European single market and customs union.

The Highland MP believes there exists a parliamentary majority to achieve a soft Brexit as many observers believe Labour is slowly edging towards the position advocated by the SNP, Plaid Cymru, the Liberal Democrats and the Greens retaining greater European status.

Labour believes in joining a “single market-variant” and “a” customs union, which means “full participation in the single market,” including “easy movement” of people.

Before Christmas Mr Blackford told The Herald that he believed opinion at Westminster was “shifting” towards a softer Brexit and that the “hard Brexiters feel as if they are being pushed back”.

SNP HQ noted how Britain’s membership of the single market and customs union could be secured if Labour and soft Brexit Tories got behind the campaign.

“As we move into the crucial second phase of the Brexit negotiations, it is now absolutely vital that we have an effective cross-party effort to safeguard our membership of the single market and customs union,” said Mr Blackford.

“Extreme Tory Brexit plans to drag Scotland and the UK out of the single market would cause catastrophic damage to the economy, costing hundreds of thousands of jobs and hitting people’s incomes, livelihoods and living standards for decades to come.

“It is time for MPs of all parties to put politics aside and work together in the national interest, to protect our place in the single market and customs union. Short of retaining our EU membership, that is by far the least damaging option, the best compromise, and the only way to protect jobs, incomes, and workers’ rights.”

The 'rainbow' summit will take place on Monday, January 8 – the first day on which the House of Commons returns from its festive break.

The party leader noted that the recent successful amendments to the EU Withdrawal Bill, when opposition parties worked together effectively to defeat Theresa May’s Government, showed it was possible to secure a parliamentary majority and deliver positive change in the national interest.

“Those who say they care about people’s jobs and incomes must now look at the evidence, look at their conscience, and get behind cross-party efforts,” declared Mr Blackford.

“Anyone who stays on the fence and allows dogmatic Brexiteers to drag us out of the single market, will bear equal responsibility when people’s jobs are lost and their incomes are slashed.

“More than ever the UK desperately needs strong leadership and straight talking, honest politics; that is what the SNP will continue to provide as we focus our efforts on retaining our place in the single market to protect our economy and safeguard jobs,” he insisted.

In his letter to opposition party leaders, Mr Blackford pointed out how recent Fraser of Allander analysis had suggested leaving the single market would risk up to 80,000 jobs and £2,000 per person in Scotland every year while a Bank of England report warned 75,000 jobs in the City were at risk with a hard Brexit.

“Across the UK, hundreds of thousands of jobs would be at stake alongside people’s incomes, livelihoods and living standards,” he wrote.

But the Nationalist leader claimed it was not only the economy that needed protection, highlighting how the communities along the land border between Ireland and Northern Ireland needed certainty for their own livelihoods that the UK staying in the single market would provide.

“The SNP have been clear: work with us to keep the UK in the single market and stop a catastrophic Tory Brexit which threatens jobs, the economy and the Good Friday Agreement,” he added.