The UN Security Council has voted unanimously to extend the mandate of Nato-led troops in Afghanistan for a year.

It urged that the mission be reinforced as a resolution called on member states to "contribute personnel, equipment and other resources" to the International Security Assistance Force.

The renewal comes as US President Barack Obama's administration is locked in a series of meetings on future troop deployments.

The UN mandate renewal was fully expected but the resolution also stressed the need for reinforcements.

But Britain's ambassador to the UN, Sir John Sawers, denied this meant a specific call to increase troop levels. He said: "We should have the forces there necessary to deliver on the tasks."

The Isaf force in Afghanistan has about 67,000 troops from 42 countries, about two-thirds from the US.

However, sources close to the "war council" meetings at the White House have suggested that the US administration is discussing whether it could work with "reconcilable" elements of the Taliban and concentrate on targeting al Qaeda at their bases near Pakistan.

Mr Obama is poised to accept Taliban involvement in running Afghanistan as he refocuses US involvement in the eight-year-old war. White House officials said the President was also considering sending troops in numbers sufficient merely to contain al Qaeda terrorists in the region.

Both proposals emerged after a meeting of the "war council" and were also discussed in a telephone conversation yesterday between Mr Obama and Prime Minister Gordon Brown.

Britain has more than 9,000 troops in Aghanistan, the biggest deployment after the US.

The President's latest tactics have angered Republicans, who say the move appears to contradict the recommendation from his top commander for up to 40,000 extra troops.

General Stanley McChrystal said the troop surge was needed to defeat the Taliban.

Mr Obama is thought to be leaning towards what aides have called the "Biden option" - a plan by vice president Joe Biden to scale back operations against the Taliban and instead focus the fight solely on al Qaeda.

Recognising that the Taliban may never be completely defeated, Mr Obama has talked before about inviting moderate Taliban leaders to play a role in the Afghan government.

It could also see parts of the country turned over to the Taliban.