Up to 12 SNP MSPs could join a campaign to urge the party to retain its stance against the international nuclear organisation. An SNP whip admitted there could be a "rammy" over Nato at the party's autumn conference.
SNP activists will be asked to back a motion by the party's defence spokesman Angus Robertson that an independent Scotland would "maintain Nato membership subject to an agreement that Scotland will not host nuclear weapons".
However, a rival amendment will also ask conference to resolve that the "SNP position will be that Scotland should not remain a member of Nato".
It has been tabled by Jamie Hepburn, SNP MSP for Cumbernauld and Kilysth, who has described Nato as a "destabilising factor in the West's relationship with Russia".
Another five SNP MSPs have also confirmed they will oppose Nato membership. They are John Finnie, Dave Thompson, Jean Urquhart, Sandra White and John Wilson. Around the same number are thought to be on the brink of publicly coming out against the move.
In all, as many as 12 SNP MSPs could join a campaign against Nato membership to be launched at the Scottish Trades Union Congress at the end of this month, it was reported yesterday .
The First Minister has made clear that he will vote for Mr Roberston's motion, potentially ending decades of SNP opposition to joing Nato,
However, despite the opposition to his stance from his party leadership, Mr Hepburn said he was looking forward to having a "debate" on the issue at the conference.
Mr Thompson, MSP for Skye, Lochaber and Badenoch, said: "The main problem for me with Nato is that it is a nuclear alliance with a first-strike nuclear policy, which is extremely worrying.
"I think it would also make it much more difficult for us to argue the case for removing Trident from Scotland if we are going to be a Nato member. I'm absolutely opposed to nuclear weapons. We should be working much harder to get rid of them."
Mr Wilson, a Central Scotland MSP, said he wanted an independent Scotland to remain outside Nato, suggesting the organisation was increasingly acting as a military proxy for America.
He told our sister paper the Sunday Herald: "I continue to support the current party policy on Nato and hope conference supports that position."
A Scottish Conservative spokesman said: "Alex Salmond has been opposed to Nato for three decades and his sudden support for membership has everything to do with the referendum."
An SNP spokesman said: "SNP members have the democratic opportunity to make their views on Nato membership clear at conference, where we expect to have an excellent debate on defence policy, including reaffirming the party's strong anti-nuclear stance."
A Sunday newspaper yesterday reported the Scottish Government was considering ways to get around Westminster's opposition to putting two questions to voters. Edinburgh and London are wrangling over the wording of the independence poll, due to be held in 2014.
The Coalition Government last night made it clear it would not accept an independence ballot paper that asked voters if they wanted greater devolution.
A Scotland Office spokesman said: "Independence and devolution are two different things that do not belong side by side on the same ballot."
A Scottish Government spokesman said: "The terms and timing of the referendum must be decided in Scotland, by the Scottish Parliament – and that includes the issue of a possible 'more powers' option in the referendum."