The recently retired UK ambassador to Nato has revealed she is voting Yes to Scottish independence and insisted the international alliance would welcome the new Scottish state.

Dame Mariot Leslie has challenged the warnings of former Nato deputy supreme allied commander in Europe Sir Richard Shirreff, who described the SNP's defence policy as "dangerous" and "amateurish" at the weekend and said Scotland's future in Nato is "uncertain" if it leaves the UK and expels nuclear weapons from the Clyde.

Dame Mariot, who was born in Edinburgh and retired as the UK's permanent representative to Nato earlier this year, said she draws "a different conclusion" from Sir Richard.

"I am sure that it would be in Scotland's interest to join Nato and to continue to anchor our own defence in a wider alliance of Western democracies," she said in a letter to The Scotsman.

"But I am also in no doubt that the other 28 Nato allies would see it in their interests to welcome an independent Scotland into Nato.

"No ally would wish to interrupt the integrated Nato defence arrangements in the North Sea and North Atlantic - least of all at a time of heightened tension with Russia.

"A democratic, non-nuclear Scotland with strong military and technological traditions would fit naturally alongside similar Nato members in Northern Europe, and would be likely to join them - and the UK - in looking for multinational solutions to the pressures on their defence budgets.

"Comparisons with Ukraine and Georgia are out of place. There is no 'queuing order' for membership of Nato. Each candidature, and its timing, is considered separately on its own merits by the Nato council. I shall be voting Yes on September 18.

"I am a democrat, and believe that the geography, economy, demography and politics of our country are so distinctive that they are best served by our own sovereign government.

"I nonetheless have affection for the UK, am proud to have been a British diplomat for more than three decades, and have enjoyed working with our highly professional armed forces and security agencies.

"Of course the closest and most important defence and security relationship for an independent Scotland would be with the United Kingdom.

"It's clear that as Scotland made the transition to independence there would be some tough negotiations over defence, nuclear and wider security questions, because there is a lot at stake on both sides.

"We are already witnessing some staking out of positions.

"But nothing in my long experience of British or international security makes me think that either country need emerge as a less safe place when those negotiations were concluded."