European nations must stop relying so heavily on the United States for global security and must take on more responsibility in their “own back yard”, the Defence Secretary Philip Hammond said today.

European countries must also be "prepared, if necessary, to take a bigger role in relation to North Africa and the Middle East", Mr Hammond said, in comments likely to be picked up with interest abroad.

"With the United States reflecting, in its strategic posture, the growing importance of the developing strategic challenge in the Pacific, the nations of Europe must find the political will to take on more responsibility for our own back yard, and fund the capabilities that allow us to do that," Mr Hammond told defence chiefs and military contractors at the Chief of the Air Staff's Air Power Conference 2012, organised by the Royal United Services Institute.

"Certainly that means shouldering the major burden in the Balkans and the Mediterranean but also being prepared, if necessary, to take a bigger role in relation to North Africa and the Middle East.

"The bottom line is that Europe, as a whole, needs to do more, at a time when the reality is that, across the continent, aggregate defence expenditure is certain to fall in the short term and, at best, recover slowly in the medium term.

"So the challenge is stark: if we can't spend more, we must do things differently - maximising the capability we can collectively squeeze out of the resources we have, increasing inter-operability, closing capability gaps through joint working and greater specialisation."

Mr Hammond also said that upgrading Britain's current Trident nuclear deterrent would probably be cheaper than any alternative proposed by the Liberal Democrats. He said that the Trident missiles and warheads have "many, many years of life in them" and only require new submarines to carry them by 2028. Any alternative attempt to create a nuclear deterrent in its entirety would be prohibitively expensive, he said.

His comments deepen the Coalition's rift over Trident, after Mr Hammond earlier this week ordered £350m of work on new submarines.

The Lib Dems accused him of "jumping the gun because no decision is due on replacing the system until after the next general election, in 2016.