More than 4,000 people, a quarter of them civilians, were killed in fighting last year, the most violent year since the Taliban were ousted in 2001. Nato commanders and analysts warn this year could be just as bad or worse.

As the harsh winter snows melt, the insurgents have resumed their attacks, mostly in the south, where they have captured a major town and have threatened a key hydroelectric dam.

Mullah Abdul Rahim, the Taliban's operational commander for southern Helmand province -- the opium centre of the world's major producer -- said militants would step up attacks in spring.

"As the weather becomes warm and leaves turn green, we will unleash bloody attacks on the US-led foreign troops," Rahim told Reuters by satellite phone from a secret location.

"Our war preparations, especially in southern Afghanistan and in Helmand province, are complete and for this our 10,000 fighters are ready to take up arms the moment they are ordered."

Ater attempts at conventional pitched battles failed last year, the Taliban are expected to return to more conventional guerrilla tactics against government forces and the roughly 45,000 foreign soldiers in the country.

A key tactic is expected to be suicide bombings, which rose dramatically last year, killing more than 200 people, but which still remain much rarer than in Iraq. The Taliban say they have 2,000 suicide bombers ready and another 3,000 in training.

Rahim said the focus of attacks will be southern areas, where the Taliban was born.

In Kandahar Taliban militants hanged three Afghans after accusing them of informing US and Nato military forces about rebel bases and hideouts, police and the extremist movement said Friday.

The men hanged in the Gereshk area of the southern province of Helmand on Thursday were two "ordinary villagers" and a former policeman who had surrendered to the rebels, a police officer said on condition of anonymity.

The officer rejected the charge that they had been spying.