David Cameron has unveiled plans for creating a cross-party 'war cabinet' to oversee operations in Afghanistan as he kicked off a potentially long run-in to the general election.

The Tory leader said the move would be part of a new style of government which focused on "unity" and consensus rather than tribal political interests.

Opposition leaders would be invited into top-level meetings "on a regular basis" to consider strategy for the military campaign.

"When a nation is at war it needs to come together and to pull together," Mr Cameron told an audience in Oxfordshire.

Mr Cameron's first speech of 2010 struck a more positive tone about Britain's prospects after his warnings over the past few months that the country faces an era of economic "austerity".

Recapping the party's policy platform, he promised that a Tory victory at the election - due to be held by June - would mean the UK had a "bright economic future".

"If we win this year's election Britain will be under new economic management," Mr Cameron said.

"We will send out the loudest signal that this country is back open for business and ready for investment.

"Decline is not inevitable. Confidence can return. If we take action now - to get a grip on the public finances and unleash enterprise - Britain can have a bright economic future."

Speaking at the Oxford School of Drama in Woodstock, against a backdrop of a picture of the Houses of Parliament with the slogan 'Year for Change', he said: "It's a brand new year. A new decade is fresh before us."