The United Kingdom could be forced to give up its nuclear deterrent if Scotland votes for independence, a former Cabinet minister warned today.

Conservative Lord Forsyth of Drumlean, a former secretary of state for Scotland, warned separation would have a major impact on the defence of both countries.

The submarines carrying the UK's Trident nuclear warheads currently operate from the Faslane naval base on the Clyde and there are potential problems with finding a suitable alternative location in England.

In a House of Lords debate ahead of a vote on independence later this year, Lord Forsyth said: "What happens if Scotland leaves the United Kingdom? Where is our nuclear deterrent?

"Let along the effect on Scotland - the loss of 10,000 jobs at Faslane, the loss of the future defence contracts at the shipyards, the jobs and everything else - what about the position of the United Kingdom, forced I think in practice to give up its nuclear deterrent?"

He said Scotland would also be "cut off from the intelligence sharing" that helped to prevent terrorism.

And he asked: "What of the British army and the other armed services. Are we to say, as (First Minister) Alex Salmond proclaims, to the men and women, the Scots, who fought in Afghanistan and fought in Iraq bravely with a Union flag on their shoulders, you have got to choose between the British army and Alex's Dad's Army?

"You have got to choose to be in effect mercenaries working for a foreign country or go off to this half-baked idea. It's insulting."

Pointing to the success of the Union, he said: "Together - Scotland and Wales and England and Ireland - we saved Europe three times: first from Napoleon, second from the Kaiser and third from the Nazis.

"When the bombs were falling the East End in the Blitz and in Clydebank in Glasgow, we knew we were one nation and we were one nation forged over the centuries and it is a disgrace that people should seek to break that family tie, that bond which has been created through our history and our common heritage, without any single indication of why it could be justified."

He said UK minus Scotland would be a "rump" and an "object of curiosity around the world".