Sir Alan says "very different" threats could emerge Admiral's interview

Admiral Sir Alan West, who was First Sea Lord from 2002-6, said "an extremely dangerous world" demanded increased spending on the armed forces.

He also warned against an "arrogance" that assumed Britain's future threats would come only from terrorism and Middle East conflict.

The next 50 years could see "very, very unpleasant" threats, he said.

Sir Alan told BBC Radio 4's Today programme: "We are in an extremely dangerous world.

"I'm afraid to say that in the next 50 years there might well be something very, very unpleasant and very different from anything anyone has predicted and I believe we need a powerful maritime force to look after this island."

He said Britain's future safety depended particularly on maintaining its maritime strength and called for extra destroyers, frigates and aircraft carriers.

'Grown-up debate'

"I think there needs to be a real debate about the amount of money spent on defence," Sir Alan said.

"If one looks at the things the government wants us to do around the world, we probably need more money for defence and there needs to be a very grown-up debate about that."

Sir Alan cautioned it would be "very dangerous" to assume Britain's future defence needs would be dominated by counter-terrorism and peace-keeping tasks.

Speaking on the 25th anniversary of the end of the Falklands War, in which he served, Sir Alan said maintaining Britain's sea power was also vital for the country's success on the global stage.

A Ministry of Defence spokesman said the defence budget had been rising above inflation since 2000.

"In 2007-8 the defence budget will be �33.4bn. We also spend some �6bn a year on world-class new equipment for the armed forces," the spokesman said.