NICOLA Sturgeon has come under renewed pressure clarify whether the SNP will promise a second independence referendum within in the next five years.

Labour and the Lib Dems claimed the SNP was planning another poll, amid growing evidence Nationalist election candidates expect a swift re-run.

Ms Sturgeon refused to rule out a fresh vote when she was challenged during the penultimate First Minister's Questions before the election.

She faced questions as Jim Sillars, a former SNP deputy leader, said he believed the party would promise a second referendum in the run-up to next year's Holyrood election.

Mr Sillars, a prominent Yes campaigner last year, said grassroots members would insist on it and he called on Ms Sturgeon to demand control over the timing of a referendum as her price for propping up a minority Labour government.

Scottish Labour yesterday listed eight SNP candidates who were on the record as describing the election as a stepping stone to a referendum.

Kezia Dugdale, Scottish Labour's deputy leader, challenged Ms Sturgeon to confirm last September's poll was a "once in a generation event," a claim made by the SNP leader in the days before the vote.

Willie Rennie, the Scottish Liberal Democrat leader, urged her to rule out a vote within the next five years.

He told MSPs: "The First Minister could make it quite clear today. It is very simple.

"We are not even asking her to rule it out for a lifetime-just rule it out for the next session.

"That is what we are asking for. Why can she not do that?"

Ms Sturgeon claimed Labour was "resorting to desperate scaremongering about a referendum that nobody is proposing".

She said Labour, which is facing wipe-out in Scotland next Thursday according to opinion polls, was "in its death throes" and said a referendum would only be held if there was a significant change in the country's circumstances since

last September.

She stressed a referendum could only take place if the SNP won a mandate for one at Holyrood.

Ms Sturgeon has sought to dampen expectations of an early re-run among the SNP's 105,000 members, most of whom joined after campaigning unsuccessfully for a Yes vote.

In an interview with The Herald last week she described party members as a "pragmatic bunch" who understood the country would not be rushed into another decision.

But commenting earlier in the day, Mr Sillars said: "I cannot believe that there will not be a commitment to independence and a referendum in an SNP manifesto next year, with the timing of the referendum to be left to a decision when we think the time is right.

"Now, that could be within a short period or within two or three years, one doesn't know, you have to wait and see what the dynamics of the politics are.

"The important thing is that next time there is a referendum we pick the time when we are going to win."

He added: "My view of a pretty pragmatic bunch, who joined the party in their tens of thousands, is that, like me, as a member we would want a clear commitment to independence and another referendum at a pragmatic time in the manifesto next year."

Speaking after First Minister's Questions, Ms Dugdale said:

"The fact that Nicola Sturgeon couldn't even repeat her own promise from last year that the referendum was a once in a lifetime event says it all."