The SNP will propose another independence referendum in its manifesto for re-election to Holyrood next year, according to a former deputy leader of the party.

Jim Sillars said the tens of thousands of new members who joined the SNP in the wake of the No vote in last year's referendum will expect a commitment to another referendum "when we think the time is right" to secure a victory.

The referendum "could be within a short period or within two or three years", Mr Sillars said.

The nationalist veteran, husband of the late SNP trailblazer Margo MacDonald, also expects the SNP to demand the constitutional right to hold another referendum at the time of the Scottish Parliament's choosing in exchange for supporting a minority Labour government.

"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," he said.

"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.

"I would hope that one of the demands that are made on a minority Labour government by the SNP keeping them in office is that they transfer the constitution from schedule 5 of the 1998 Act from Westminster to Holyrood."

The last referendum had to be signed off by Westminster in the Edinburgh Agreement under current constitutional law.

SNP leader Nicola Sturgeon has said she will know in her gut when the time is right for another referendum and the decision "will be down to not what the SNP wants, or what the SNP thinks is right, but what I think is right for Scotland and what I think the people of Scotland want".

She also said SNP members are a "pragmatic bunch" who understand that another referendum cannot be rushed.

Mr Sillars said: "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."

He said there will be "no talk of sanctions whatsoever" if Ms Sturgeon decides to withhold a commitment to another referendum next year.

"We've got 100,000 people, it's a democratic party, there is a national conference to come and national councils to come when the membership will express its point of view and the leaders will express their point of view, and I am hopeful that they coincide," he said.

"No one inside the SNP is at war with each other or Nicola Sturgeon.

"I understand that the media is absolutely desperate to get something that would indicate anxiety within the SNP.

"There isn't any on my part. I have expressed an opinion and I am happy to stand by that opinion. I could be wrong, but I don't think I am."

Speaking at First Minister's Questions, Ms Sturgeon said: "Let me make it quite clear, I've got the greatest of respect for Jim Sillars but the clue is in his title, former deputy leader of the SNP.

"I'm the current leader of the SNP so let me say it clearly once again. This election is not about independence. It's not about a referendum. It's about making Scotland's voice heard."