Boris Johnson says Brexit 'done right' could strengthen union
Boris Johnson has claimed Brexit "done right" could "cement and intensify" the union between the UK nations.
He said Scotland would be "less likely" to support independence after the UK leaves the EU.
Both candidates in the Conservative leadership battle have set out their opposition to a second independence referendum at a digital hustings.
Jeremy Hunt said his party had been complacent about the union and vowed never to allow the break up the UK.
The two leadership contenders answered a range of questions in a digital hustings, streamed on the Conservative Party's Facebook and Twitter accounts.
On the issue of a possible second independence referendum, Mr Johnson said Scottish voters would not want to rejoin the EU because of its effect on relations with England.
'Sensibly and effectively'
He said: "If you Brexit sensibly and effectively, you take away so much of the ammunition of the SNP," he said.
"Are they really going to want to join the European Union, to join the euro, to join Schengen, to submit Scotland to the full panoply of European laws? Of course they are not."
He went on: "Get Brexit done right, and I think we can cement and intensify the union. There are things you need to do on coming out of the EU legally, to underpin the whole UK single market and we will use every opportunity to strengthen the union, not just with Scotland, but with Northern Ireland as well."
The SNP-led Scottish government is seeking another independence vote, with one opinion poll at the weekend suggesting 53% would back leaving the UK if Mr Johnson became prime minister.
His rival in the leadership contest, Jeremy Hunt, said that the Tories had been "complacent" about the union since 2014 when Scottish voters rejected independence by a margin of 55% to 45%.
He said he would "never, never, never" allow the break up of the UK although he has previously challenged Scotland's first minister, Nicola Sturgeon, to win an outright majority at the next Holyrood election if she wants to hold indyref2.
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He said: "I don't want to go so far as to say I'm the living embodiment of the union but I do have Welsh blood and I do have Irish blood and I did two very happy years of my childhood in Scotland."
He added: "I just want to be very straight forward about this: I will never allow our union to break up, never, never, never."
Ms Sturgeon insists she already has a mandate for another referendum, following her party's success in the 2016 Holyrood election.
There is an SNP-Green majority for a referendum in the Scottish Parliament but Ms Sturgeon has made it clear she would like any future vote to be held with the agreement of the UK government.
A majority of Scottish Conservative MSPs have backed Jeremy Hunt to be the next prime minister.
Following party leader Ruth Davidson's announcement on Wednesday that she would support the foreign secretary, 18 further MSPs signed a joint letter to back his bid against rival Boris Johnson.
More than half of the party's 31 MSPs have signed the letter, including deputy leader Jackson Carlaw.
Ms Davidson told BBC Scotland that she backed Mr Hunt because "he's puting the strength of the union above everything else", challenging Mr Johnson over his comments about leaving the EU by 31 October "do or die".
She said: "I want to see him make assurances that it's not Brexit do or die, it's the union do or die. That's exactly what we've seen from the other candidate in the race, and that's why he's going to get my vote."
Mr Hunt's public support is more sparse among Scottish Conservative MPs with three of the 13 representatives at Westminster putting their names to the letter - John Lamont, Bill Grant and Paul Masterton.
Among the Scottish Conservative MPs backing Boris Johnson is Ross Thomson, who is running his campaign in Scotland.
Douglas Ross, Colin Clark and Andrew Bowie also support Mr Johnson for the top post.
The winner of the contest, which will be decided by a vote of about 160,000 Conservative Party members, will take over from Theresa May on 24 July.