John Finnie and Jean Urquhart were among eight MSPs who led a grassroots revolt against the leadership's plan to take an independent Scotland into the nuclear armed military alliance.

The U-turn split the party almost down the middle when it was voted on at the SNP conference in Perth last week.

Defence spokesman Angus Robertson was booed by some party members as he made a final plea to reverse its 30 years of opposition to Nato.

Delegates voted 394 to 365 against an amendment signed by Mr Finnie and Ms Urquhart, which would have rejected full Nato membership.

Both are Highland and Island list MSPs.

SNP leader Alex Salmond said: "I'm saddened that Jean and John have decided to resign from the party.

"They have been excellent servants to the SNP, and I'm grateful to them for their tireless efforts.

"We had an excellent and democratic debate at party conference last Friday, and agreed a policy of reaffirming our opposition to nuclear weapons as a non-nuclear member of the Nato alliance – a position that will be accepted by the party as a whole.

"Jean and John have indicated to me that they will continue to support the Government from the back benches, and I welcome that.

"I also look forward to working with them both in the campaign to achieve a Yes vote in Scotland's referendum in 2014."

Mr Robertson insists that Scotland will only remain in Nato on the condition that it will be allowed to remove nuclear weapons from the Clyde.

The rebels feared that Scotland will face pressure to retain them if it remains in Nato.

They also raised concerns that an independent Scotland will be beholden to the interests of the USA and UK Governments.

Justice Secretary Kenny MacAskill, who drew a US backlash after releasing Locker-bie bomber Abdelbaset al-Megrahi, was widely credited with swaying the conference vote to reject the rebel amend-ment by declaring that he is "certainly no US lapdog".