FORMER prime minister Gordon Brown urged Conservative leadership candidates to "think again" on telling Scotland to "get lost".
His comments came after Tory leadership candidate Liz Truss said she would "ignore" Scotland's First Minister, Nicola Sturgeon.
Speaking at leadership hustings in Exeter, Devon, the Foreign Secretary called Ms Sturgeon an "attention seeker", as she refused calls for a second referendum on Scottish independence.
Ms Truss is currently the frontrunner in the leadership race, which would see her replace Boris Johnson as Prime Minister.
But Mr Brown, Labour prime minister from 2007 to 2010, said Ms Truss's approach was "ridiculous" if she wanted the British union to "survive".
Mr Brown has been a strong campaigner against independence and had previously intervened in the first referendum in 2014 to make Scotland's case for remaining part of the UK.
He helped develop The Vow, where then leaders of Labour, Conservative and Liberal Democrats pledged more powers for Holyrood as an alternative to independence.
Speaking at the Edinburgh fringe show The Political Party With Matt Forde, the former Kirkcaldy and Cowdenbeath MP said: "I don't think you deal with Scotland the way Liz Truss or Rishi Sunak or Boris Johnson deals with Scotland."
He told the McEwan Hall audience that both candidates needed to "co-operate" with Scottish politicians on the constitutional issue.
He said Ms Truss was attempting to take a "domineering attitude" where telling "Scotland to get lost" was the best approach.
He added: "That is a complete mistake, because the one person in the country who's got the responsibility in the country to try and bring the country together, is the prime minister.
"And you've got to be in a position to say, look let's co-operate on things where we can work together.
"You cannot just say I'm not going to talk to you at all. It's a ridiculous position."
He added: "The only way that the union or Britain will survive is if people find better ways to work together.
"I would argue that the Tory leaders should think again and there should be a fresh start attempted in the relationship between the British Government and Scotland."
Ruth Davidson will "always" return to campaign against a Scottish independence referendum, she told an audience at an Edinburgh Fringe show.
Baroness Davidson, the former Scottish Conservative leader, was a guest at Iain Dale's All Talk show at the Pleasance Theatre, in the Edinburgh International Conference Centre on Sunday.
While she stepped down as leader in 2019, she has remained a prominent figure for the party in the campaign against independence.
When asked whether she would ever come back and "stand up to Sturgeon", she said: "First of all, were there to be one [a referendum], I will always come back and get involved in whatever way I can because I believe in it and I believe in fighting for what you believe in."
But she said: "I honestly don't think there is going to be one within the next sort of 10 to 15 years - and by which point, politics will have moved on so much that people won't have a clue who I am."
Meanwhile, in a separate event at the Edinburgh fringe, Baroness Davidson said that "she wouldn't have to be asked" by the party or prime minister to get involved.
But a return to frontline politics has been ruled out by the former Edinburgh Central MSP.
She said: "I think my time in elected politics is over."
In July 2021 she was given a life peerage in the House of Lords.
And she took aim at the current Scottish Government plans to hold a referendum in October 2023 - depending on the outcome of a Supreme Court ruling on the vote's legality.
She accused First Minister Nicola Sturgeon's party of "weakness" by pledging to use the next general election as a "de-facto referendum".
She said: "That is a sign of weakness, that they don't know what their next move is but they needed to do something.
"I'm not sure that plan is one that is wholly effective."
Ms Davidson also said she did not "understand the logic" of the SNP's desire for a second referendum.
Despite the SNP and Greens standing on manifestos to hold a new vote on independence and winning a majority of seats in the Scottish Parliament, Ms Davidson said they should respect the result of the 2014 referendum.
"I don't think you get to keep running a question because you didn't like the answer," she said.
"I fundamentally disagree with that."
But an SNP spokesman said the Scottish Government "has been given a cast-iron democratic mandate by the people to hold an independence referendum".
"Ruth Davidson said that if there was a majority of parties in the Scottish Parliament who supported independence then it is right that an independence referendum be held, and clearly that is the case," the spokesman said.
"In any case, it is the Scottish people who will decide upon the future of Scotland - not a Tory government at Westminster or unelected Lords with no democratic mandate."