The SNP’s youth wing has rebelled over plans for a U-turn on the party’s historic opposition to Nato membership.

The group said its membership had reached a “clear and united decision” to support a rival amendment to a motion backed by Alex Salmond that an independent Scotland would retain Nato membership.

David Linden, national convener of the SNP Youth,  said its national executive committee had voted to support the alternative that Scotland should withdraw Nato membership altogether when the motion comes before the party conference this autumn.

He said: “The party’s youth wing has a proud history of campaigning against nuclear weapons.

“I don’t imagine Alex Salmond is pacing up and down Bute House worrying about how the youth wing might vote, but young people make up a significant percentage of the party membership so I would certainly hope he will take notice of what we think.”

SNP members will be asked to vote on the issue at the party’s annual conference in October.

A party spokesperson said: “The SNP has a cast-iron commitment to rid Scotland of nuclear weapons.

“Given the continued presence of Trident nuclear weapons in Scotland – against the wishes of her Parliament and people – independence is the only constitutional option which makes this possible.”

Meanwhile, MPs have challenged the Scottish Government’s right to call an independence referendum, with Labour MP Ian Davidson claiming in a report today that the “overwhelming weight of evidence” shows Holyrood cannot legislate to hold a referendum on separation.

The report also demands any final arrangements for a referendum should be subject to a triple lock by Westminster – approval through a Section 30 notice, then scrutiny by the Scottish Affairs Committee, before final “approval by Scotland’s MPs”.