Soldiers, sailors and airmen serving with the British armed forces may be unwilling to sign up for a new independent Scottish defence force, Defence Secretary Philip Hammond warns.

In a speech in Edinburgh today, Mr Hammond will describe the SNP's plans for the defence of Scotland if it succeeds in gaining independence as a "significant gamble".

A Scottish defence force would be able to offer only a "fraction" of the opportunities available in the British forces, he will say, making it difficult to attract high-calibre recruits.

In an interview ahead of his speech, Mr Hammond ridiculed a SNP promise to keep 15,000 service personnel in Scotland, suggesting it was like telling recruits: "Join the Navy and see the Clyde."

However, the comment have provoked a strong backlash, with SNP Westminster leader and Defence spokesman Angus Robertson MP claiming that the Defence Secretary has only come to Edinburgh to ‘insult Scottish service personnel’.

He will say in his speech: "One of the challenges any armed forces around the world will face is how to attract and retain high-quality recruits. And the key to recruitment and retention is the quality of the offer you are able to make to potential recruits," he will say.

"The British armed forces are able to attract some of the highest calibre recruits because they are able to offer some exciting and demanding career opportunities, with the chance to deploy overseas on operations and training and with the cache of being among the best and most widely respected armed forces in the world.

"The nationalists have taken for granted that soldiers currently serving in the 'Scottish' regiments would want to serve in a Scottish defence force. But who knows how many Scots would want to serve a new state as part of a Scottish defence force?

"They certainly wouldn't have a fraction of the opportunities they currently have for overseas deployment and training, nor the diversity of experience or access to the quality of kit and equipment with which they currently operate.

"It is a significant gamble to assume that troops in our UK armed forces would volunteer for a Scottish defence force. All of this adds up to a set of serious questions about the SNP's military personnel plans."

He said the nationalists' plans to annex the Scottish regiments from the Army and a share of other UK defence assets lacked coherence.

"Taking random units and putting them together does not make an army. Half a destroyer would be no use to anyone, neither would be one frigate," he said.

Mr Hammond announced last week that the number of service personnel will increase by about 600, far fewer than the thousands promised in 2011 by his predecessor Liam Fox.

The SNP used the opportunity to demand an apology for what it called a shameful breach of trust in the number of troops being sent to Scotland.

Angus Robertson MP, the SNP Westminster leader, said Mr Hammond's trip to the capital should be accompanied by an apology.

He said: "The brazen nature of the basing review took everyone aback and Mr Hammond should say sorry to Scotland.

“It was too much to hope that on one of his very rare visits to Scotland Philip Hammond might want to explain why the coalition reneged on all its commitments in the basing review last week .  He should have seen it as an opportunity to apologise for the broken promises and u-turns made over the deployment of up to 7,000 troops which turned into just 600.
 
“You could be forgiven for thinking that he might want to come and eat humble pie for all the dissembling and distortions.  He may even have taken  a rare moment to explain why he thinks it is a good idea to spend billions and billions of pounds  dumping weapons of mass destruction on the Clyde despite massive opposition from all sections of Scottish society.
 
“Not a hope. He came to attack the SNP and Scotland - something he could easily have done from his office in London, and he could have saved the taxpayers a return ticket.   He came to insult Scottish service personnel and demean his office by making jokes  about Scottish defence needs. People will make their own judgements about the wisdom of making that kind of speech when the reality is it his government that has been part of a massive defence underspend of over £7 billion pounds in Scotland in the last ten years alone, and has cut the defence footprint in Scotland relentlessly over the  years. It is his government that has made a volte face over all its promises . No one else to blame .
 
"The truth is that independence offers the attractive full-rank career prospects in Scotland which is impossible with the current set-up. For too long Scots in the UK Armed Forces have had to spend their entire careers outside Scotland owing to postings or limited options owing to their rank or specialism. This will change significantly for the better after independence.

"Service personnel will have much greater certainty about their location in Scotland, giving a bonus to defence dependent communities. Domestic operations, training at home and with neighbours and allies as well as international participation in UN sanctioned peace-keeping missions will guarantee an attractive career path.’’