Humza Yousaf said he is “confident” the SNP can hold the constituency of Rutherglen and Hamilton West but admitted his party would face a “tough” challenge if a by-election is held there.

With a recall petition currently under way after Margaret Ferrier, the MP for the area, was suspended from the House of Commons for 30 for breaches of Covid rules, voters could force a by-election to oust her from the seat.

Mr Yousaf said: “It will be a tough by-election, there’s no getting away from that”.

Labour having been campaigning hard in the seat, hoping to capitalise on a fall in support for the SNP in polls, which has come as the party faces a high-profile police investigation into its finances.

There was also public outcry after it emerged Ms Ferrier, who was elected as an SNP MP but now sits as an independent, took a train from Scotland to London and spoke in the House of Commons while she should have been isolating while waiting for the results of a Covid test.

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The MP, who travelled back to Scotland by train after being confirmed as positive with the virus, has appealed for people not to sing the recall petition.

Mr Yousaf, who was campaigning in Blantyre in the constituency on Saturday with SNP candidate Katy Loudon, however insisted that support for his party was “rock solid”.

The Scottish First Minister and SNP leader told PA Media: “I’ve been speaking to residents, doing a lot of canvassing. Support for the SNP is very strong here.

“I’m hopeful, I am confident that we will hold on to the seat here for the SNP. Our support is absolutely rock solid from the doors I have knocked over the past few weeks and indeed here today.

“But we’re not complacent, we know it will be a tough by-election, there’s no getting away from that.

“For all the circumstances that surround it this byelection will be a tough one, that’s why we don’t take a single vote for granted, that is why I am out here personally working hard to secure as much support as we can for the SNP.”

Ms Ferrier has urged locals in the constituency not to sign the recall petition, saying her constituents are her “top priority”.

She stated: “I made a mistake for which I continue to apologise and have faced severe punishment.

“It has not deterred me from doing right by constituents and continuing to

fight on their behalf.

“I hope that my constituents will recognise this.”

Under parliamentary rules, MPs who are suspended for 10 sitting days or more are liable to face a by-election but only if 10% of their constituents sign a recall petition.