Scotland's First Minister Humza Yousaf claims a Holyrood election could be called as he refuses to say if he will resign if he loses a looming vote of no confidence.

Speaking exclusively to Sky News in Fife on Saturday, the SNP leader said it was "really disappointing" to learn the Greens could refuse to change their minds on voting against him in a ballot which could prove fatal for his leadership. Mr Yousaf has today written to all the opposition parties, including Alex Salmond's Alba party, at Holyrood urging them to rethink their plot to oust him.

The SNP leader said on Saturday that he was leaving it to his rivals to determine his fate. A Green Party source said the only letter they will accept from the first minister is his resignation.

Mr Yousaf told Sky News: "Well let me say again, that would be really disappointing if that is the Greens' position. "As I say, I've reached out to them, they are saying publicly that they're going to support a Conservative motion against independence, first minister and independence government.

"That would be, I think, a poor choice to make." Asked if there might be a Scottish election if he doesn't win the vote, Mr Yousaf replied: "Can't rule it out." The casting vote now looks likely to be Alba MSP Ash Regan who sensationally defected from the SNP in the wake of her defeat in the race to replace Nicola Sturgeon last year. Sky News understands Alba is holding an emergency meeting this weekend to determine how it will cast the key vote.

When asked how SNP members would feel about being "propped up" by Mr Salmond, Mr Yousaf said: "Let me make it really, really clear, I'll be sending out to anybody I meet with, whoever comes round that table, that these are the priorities of the SNP minority government. "This is what we'll be pursuing, this is what we'll be pushing.

It'll then be up to be it Ash Regan, be it Lorna Slater, be it Patrick Harvie or any of them, to decide what button they push when it comes to the vote of no confidence." Read more:How did we get here - and what happens next? The first minister was asked twice whether he would resign if he failed to win the confidence of parliament. He responded: "Again, I'm not planning to lose the vote of no confidence, I'm planning to win that vote of no confidence." Asked if his position would be untenable, he said: "Planning to win." On Saturday evening a Scottish Greens source said the party would respond to the First Minister "in due course"..