AN independent Scotland would not automatically become a member of Nato, the military alliance's chief said.

Jens Stoltenberg, Nato secretary-general, said in Brussels that Scotland voting to leave the UK would mean it also had to leave the defence bloc.

Mr Stoltenberg, speaking after First Minister Nicola Sturgeon announced plans to hold a second independence referendum, said an independent Scotland would then have to gain the approval of all 28 allies before it could re-join as a new country.

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Nato considers nuclear weapons a key component of its defence capability and the SNP's opposition to them may prove problematic for a future, independent Scotland's bid for membership, critics said.

Mr Stoltenberg told Sky News: "If it happens, then the UK will continue as a member of Nato but a new independent state has to apply for membership and then it is up to 28 allies to decide whether we have a new member.

"All decisions in Nato are taken by consensus, so we need the consensus of all allies.

"By leaving the UK it will also be leaving Nato, but of course it is possible to apply for membership and then the allies would then decide whether the independent state would become a member of Nato."

Trident, Britain's nuclear deterrent, is based at Faslane on the Clyde but could be moved south of the border if Scotland split from the UK.

During the last Scottish independence debate, former UK Nato ambassador Dame Mariot Leslie - who voted Yes in the referendum - claimed that “the other 28 Nato allies would see it in their interests to welcome an independent Scotland into Nato”.

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However, George Robertson, the British defence secretary between 1997 and 1999, suggested at the time that the SNP’s opposition to nuclear weapons would disrupt Scotland’s efforts to reapply for Nato membership.