THE SNP has been blamed by smaller pro-independence parties for scuppering a proposed 'Yes Alliance' to fight May's General Election.

Following victory for the No campaign in September's referendum, there were calls for the SNP, Greens and the Scottish Socialist Party (SSP) to agree to field a single candidate in certain constituencies under a cross-party banner, in an attempt to avoid a split in the pro-independence vote.

However, both the Greens and the SSP have confirmed that they will both be fielding their own candidates at the General Election, leaving the Yes Alliance proposal, which its supporters said would ensure a maximum number of pro-independence MPs at Westminster, dead in the water.

Both parties said that the SNP's approach to selecting candidates for the May General Election was to blame for the idea failing to materialise.

While the SNP has backed rule changes at its conference that would allow non-party members to stand for the party, it is envisaged that those elected would have to agree to take the party whip at Westminster even if they have not formally joined.

Colin Fox, national spokesman for the SSP, said he believed that Yes Alliance candidates would have had a better chance of unseating incumbent MPs than those standing under an SNP banner in some areas, particularly in places that voted in favour of independence.

He added: "Following the referendum, a lot of the Yes local groups met up to talk about the direction we should go in. Rank and file SNP members were very positive about this idea of an alliance.

"Through them, Stewart Hosie and Angela Constance were asked repeatedly about it at the deputy leadership hustings, and they repeatedly said they were amenable to the idea.

"We have been arguing for this for three months, but I think the SNP at leadership level decided that this isn't something they're going to do. I know Labour MPs were petrified of losing their seat and were praying for an SNP candidate so they can make it tribal.

"I think the SNP have got a little bit carried away with the euphoria of a new leader, a surge in membership and poll ratings. None of those things are going to last."

Patrick Harvie, co-convenor of the Scottish Greens, also said the SNP had blocked the proposal. "We were hoping to explore what scope there was for cooperation across party lines in the wake of the incredibly engaging referendum campaign," he said.

"Given that the SNP have decided they are not open to that kind of arrangement - which I completely understand - we will continue with branch selections. We are looking forward to putting across the Green agenda for Scotland, and across these islands."

The SNP has indicated that new members of the party should be allowed to stand as candidates in May, if they are selected by local constituencies. Previously, only those who had been members for at least 12 months could stand.

Tommy Sheppard, a former Labour Party councillor who runs The Stand comedy club in Edinburgh, is among the new SNP members who has said he is keen to seek election to Westminster.

Angus Robertson, the SNP's Westminster leader, said: "The diversity of the Yes movement was undoubtedly one of the key strengths of the campaign, and the resolution passed at SNP conference last month reflects the SNP's recognition of that fact.

"The party's National Executive Committee is currently exploring options that would allow those who were part of the Yes campaign but do not satisfy the current membership criteria for candidacy the chance to be considered for selection.

"A momentum for change is sweeping Scotland - and membership of the SNP has grown from just under 25,000 on referendum day to over 92,000 today. By being open to new people and new talent among our candidates, we can ensure the strongest possible voice for Scotland at Westminster next year."