BORIS Johnson's spokesman has said it's "clear" that the issue of independence was "settled".

His comments follow an interview with Alister Jack where the Secretary of State said there should be no second referendum until 2039 at the earliest.

Speaking to the BBC, Jack said ministers would rule out a referendum regardless of the outcome of next year’s election.

“It's no for a generation," he said.

Asked to define a generation, he said: "Is it 25 years or is it 40 years? You tell me. But it's certainly not six years, nor 10".

READ MORE: Independence: Nicola Sturgeon slams Tories' 25-40 year referendum delay

The Secretary of State added: “When you’ve had a 300-year-old enduring partnership as successful as the United Kingdom, you don’t then go into a period of neverendums until a party that has one objective, which is to separate Scotland from the rest of the United Kingdom, gets its own way."

Asked if the comments were government policy, Boris Johnson’s spokesman said: "The PM has said on countless occasions that the issue of independence was settled when the Scottish people voted decisively to remain part of the UK.

"It was billed at the time as a once in a generation vote and the Prime Minister has been clear that he believes that must be respected."

Asked if Johnson would agree that a "generation" would be between 25 and 40 years, the spokesman said: "The fact is that people voted to keep our United Kingdom together. It was billed at the time as a once in a generation vote."

The SNP’s Shadow Scotland Secretary Mhairi Black said the Tory position was “completely unsustainable, undemocratic and doomed to fail".

She also pointed out that Jack had contradicted himself. 

In 2019, he had agreed with Ruth Davidson that the SNP winning a majority at the next Holyrood election would be a mandate for a Section 30 order. 

He said: "Because the democratic mandate for a Section 30 order is a matter for 2021. We'll see whether or not the Scottish National Party get a majority then.

"I mean the Scottish National Party - not in collaboration with other parties, not in any alliances - but a Scottish National Party majority".

READ MORE: Alister Jack: No Scottish independence referendum for at least 25-40 years

Black said: “Just as Donald Trump will have to accept the will of the people if the US election goes against him, so will Boris Johnson have to accept the will of the people of Scotland in next year’s Holyrood election. 

"With poll after poll concluding that independence is now becoming the settled will of the majority of people in Scotland, it’s telling that Alister Jack is shamelessly shifting the goalposts given his previous contradictory comments over a second referendum - the Tories are rattled. 

"Scotland's interests and democratic decisions have been repeatedly ignored and discarded by a detached and broken Westminster system – it is little wonder that support for independence is growing.”