UKIP Scotland's first MEP has sparked an outcry after he said a narrow referendum win for Yes would not be a mandate for independence.
David Coburn said Yes should have to win 60% of the vote to secure independence but anything less could only produce more powers for the Parliament.
Lord Robertson of Port Ellen, a Labour peer, has also claimed there could "easily" be a legal challenge if a very close result produces a constitutional crisis.
The SNP last night condemned the remarks.
Coburn, elected in May, was the warm-up act for UKIP leader Nigel Farage at an event for party members in Glasgow on Friday night.
Speaking to the Sunday Herald, Coburn said a tight win for Yes this week should not mean Scotland leaving the UK.
"I don't think they have a mandate, to be frank, because you are taking an an awful lot of people out of the United Kingdom who don't even want to go," he said.
"I don't think it would be legitimate."
Still on the theme of a narrow victory for Yes, Coburn continued: "If I were Salmond, I don't think I'd say I've got a mandate for indepenence... I'd say I'd have a mandate for devo max. If he was a statesman, that's what he would say."
Asked what sort of victory would be a mandate for independence, he said: "60-40 would be fair.
"I think less than that is dangerous territory. You are depriving people of their nationality and nationhood."
Coburn's comments are reminiscent of the infamous 40% rule in the 1979 devolution referendum, when Westminster ruled that a simple majority was not sufficient for victory.
Instead, 40% of the population were required to vote for devolution, a hurdle that was not overcome.
In an interview with the Sunday Herald, the First Minister said he would be "absolutely delighted" with a 50.1% vote for Yes.
On a turnout of 80%, such a victory would represent just 7000 more votes for Yes than No, and suggest Scotland was deeply divided.
However, he added his ambition was to win "a convincing majority" that exceeded that margin. "I do have something [a figure] in mind but I'm going to leave it to the people," he said.
Meanwhile, Lord Robertson also said there could be questions over a slender Yes win this week.
Speaking to this newspaper in Edinburgh last week as polls showed the contest on a knife edge, the former defence secretary said he was not aware of any specific plans by the No campaign to challenge a narrow Yes result, but said legal challenges could "easily" arise.
He said: "The returning officer has said there can be no recount. If it's very, very tight, you know, you've got a real constitutional crisis.
"I'm sure that they [the Yes side] are massively spending at the moment outwith the rules.
"[For example] we saw at the Islay show the massive marquee that they had, hiring in pipers and things like that."
SNP MSP Humza Yousaf said: "David Coburn's latest bizarre outburst shows the panic that is gripping anti-independence politicians as more and more people wake up to the opportunities of a Yes vote. The Edinburgh Agreement commits both sides to respect the outcome of the referendum and people in Scotland rightly expect politicians on both sides to stick to that commitment."