Alex Salmond yesterday sought to turn the debate about an independence referendum on to his Labour rivals, challenging the governing party to explain why it will not allow Scots to choose their own future in such a ballot.

The SNP leader was continuing the campaign skirmish over his plan to publish a White Paper on a referendum within 100 days of forming an administration after the May 3 election. At the weekend, he moved to clarify the plan, to counter Labour claims he would hold the referendum itself by next September.

He said he would publish plans for a referendum along with a White Paper, but stressed he wanted to leave room in any coalition negotiations to delay the independence vote for up to four years.

Mr Salmond said: "We have shot Labour's fearmongering fox suggesting we intended to hold the referendum itself in the first 100 days of government. Labour and the other London-based parties are running scared of the referendum policy because it's so popular."

LibDem leader Nicol Stephen, the most likely coalition negotiating partner, was yesterday asked if there was common ground opening up and showed no sign of giving ground on his opposition to such a ballot.

Meanwhile, Labour sought to press home what it portrays as the SNP running away from its independence policy, publishing a list of other "flip-flops".