The violence came after a week of intense fighting as the Taliban's al-Qaeda-backed insurgency, launched nearly six years ago, intensified into the summer.

Three soldiers with the US-led coalition and their Afghan interpreter were killed near the border with Pakistan when they were hit by a bomb during combat, the force said in a statement.

Taliban fighters were responsible for the attack in Nangarhar province, a spokesman told AFP by telephone, claiming the soldiers were US nationals.

The coalition withheld their nationalities but most of the international soldiers in eastern Afghanistan are from the US military.

Earlier, the British defence ministry announced that a British soldier was killed and five wounded after their patrol came under fire from Taliban insurgents in southern Afghanistan on Saturday.

The attack was in the volatile Sangin district of Helmand province, considered a hotbed of Islamic extremists and opium farmers said to help finance the insurgency.

Militants also ambushed an Afghan army patrol in Sangin overnight, the Afghan ministry of defence said. The attack sparked a fierce gun battle in which seven rebels were killed and seven wounded, it said.

Warplanes were called in to attack ground targets after rebels stormed an Afghan army post in southern Uruzgan province on Saturday.

"Four enemies were killed and their bodies are still at the battlefield," the statement said. Three Taliban fighters were killed in a separate clash in the same area, it said.

The ministry also reported two Afghan soldiers were killed in the previous 24 hours but gave no details.

Militants meanwhile tried to overrun a district police headquarters in Wardak province overnight, sparking five hours of fighting which left four of the attackers dead, police said.

In neighbouring Ghazni, where the Taliban are holding 21 South Korean hostages, Afghan and coalition troops clashed Saturday with insurgents, four of whom were killed, they said.

An international military operation drove the Taliban out of government in late 2001 when the hardliners did not hand over their al-Qaeda allies in the weeks after the 9/11 attacks.

But the hardliners have been able to regroup in recent months and carry out daily attacks aimed at undermining the new administration.