Mr Yousaf said: "We've been very clear it's not for Jeremy Corbyn, neither Boris Johnson, it is for the Scottish people and the Scottish Parliament to decide when there should be another independence referendum, and we want to hold one in 2020, as the First Minister has said."

Mr Yousaf added: "Jeremy Corbyn's position on this has shifted a number of times already in what is a relatively short campaign. I suspect what he says now will not necessarily be what he says when he needs the keys to Number 10."

• READ MORE: Ian Blackford: 'Our country's desire for Scottish independence is unstoppable'Pushed on whether he believes there will be room for manoeuvre to get a second Scottish independence referendum after the election, Mr Yousaf said: "I think Nicola Sturgeon put it pretty clearly at our conference speech - don't bother picking up the phone if you're not going to talk about a second independence referendum, and that is a clear marker for us."

Fresh from his debate with Boris Johnson, Jeremy Corbyn now faces continuing calls from the SNP for an independence referendum in 2020.

Asked whether he believes Mr Corbyn will pick up the phone, he continued: "Without a doubt, because if Jeremy Corbyn wants to put forward the rest of his programme for government, his Queen's Speech, his budget, he, by current polls certainly, will need a number of partners to help him do that.

"The SNP as things stand are the third largest party in the United Kingdom, we are going to be the kingmakers, potentially."

Humza Yousaf believes 'without a doubt' that Jeremy Corbyn will allow a second independence referendum in 2020