Scottish Tory leader Ruth Davidson's threat to quit welcome: UUP

A report in the Sunday Times claimed that Ms Davidson and Scottish secretary, David Mundell, would quit in that situation because it would fuel the case for Scottish independence.

A senior Tory source told the paper: “Any differentiated deal that puts a hard border down the Irish Sea they consider a resigning matter.”

Mr Swann said: “I welcome reports of support from Scottish Conservative leader Ruth Davidson MSP and Scottish Secretary of State David Mundell MP for their position that new controls separating Northern Ireland from the rest of the UK are unacceptable.

“We have repeatedly stated that unionists who voted to remain in the EU were not voting for Northern Ireland or indeed Scotland to leave the UK. Those views must be recognised and respected and not deliberately and wilfully misrepresented.”

Mrs Swann, who claimed the “next few days will be pivotal in the history of Northern Ireland and the rest of the UK”, called into question the “value and influence” which the DUP claims to have through its confidence and supply agreement with the government.

He underlined that any deal that puts a border down the Irish Sea would be “unacceptable” to unionism.

“It’s time to wind down the rhetoric and concentrate on trying to get a sensible deal. Any border down the Irish Sea, regulatory or otherwise would be as bad as a no deal Brexit for Northern Ireland and indeed the Republic of Ireland,” he said.

“No matter what way a deal might be dressed up, any deal which opens up Northern Ireland to being treated as an EU protectorate, with regulations imposed on us by Brussels in tandem with Dublin, would be a betrayal.”