David Mundell has described the next Scottish Parliament election in 2021 as a "pivotal moment" in determining whether a second referendum on independence could be held.

Mr Mundell, who was replaced as Secretary of State for Scotland earlier this week as part of new Prime Minister Boris Johnson's Cabinet reshuffle, said that securing a unionist majority at Holyrood would prevent another vote on the issue from being held.

And he said that Mr Johnson must give his backing to Scottish Tory leader Ruth Davidson - who did not support him during his campaign to succeed Theresa May at Number 10.

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In an exclusive interview with the Scotland On Sunday newspaper, Mr Mundell said: "There's nothing inevitable about having a second independence referendum, and certainly not in the short term.

"I do think that the 2021 Scottish Parliament elections will be a pivotal moment.

"I regret that, because those elections should be about the Scottish Government's record on health and education and drugs and all the rest of it, but you can already see the direction of travel, that it is effectively going to be a referendum on a referendum."

He added: "It's a very clear message that the way to stop another independence referendum is to ensure a unionist majority in the Scottish Parliament in 2021, so that involves Boris backing Ruth to deliver."

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Mr Mundell's successor at the Scotland Office, Alister Jack, said that the UK Government would reject any request by the Scottish Government for a Section 30 Order, which would transfer powers to Holyrood so that a referendum could take place.

Asked whether such a request would be accepted, he said: "Absolutely not. We decided that in 2014."