US troops kill al-Qaeda fighters

The battle is the most serious since the Operation Anaconda

American-led forces in Afghanistan say they have killed several al-Qaeda members and detained many more in the most serious battle for over a month.

Major Bryan Hilferty said the fighting started when a joint patrol of Afghan soldiers and US special forces came under fire on Saturday.

A series of violent incidents have raised security fears this week

"We received ineffective enemy fire and we returned fire from both ground and air and killed several terrorists," he said.

There had been no casualties among the coalition forces.

This is the first real contact between the coalition troops and al-Qaeda since the battle around the eastern town of Gardez during the Operation Anaconda last month.

The Americans have given no indication of where the fighting took place this time, but the BBC's Jonathan Charles in Afghanistan says it is assumed to have occurred in the east, where al-Qaeda and Taleban resistance has been the strongest.

Wave of violence

The outbreak of fighting comes amid a series of incidents which have raised security fears in the run up to the return of Afghanistan's exiled 87-year-old king, scheduled for later this week.

There have been reports of a missile attack on Saturday on an airbase used by US troops near the southeastern city of Khost.

In Kabul, a group of about 30 men opened fire on British peacekeepers in Kabul on Friday night in the latest in a series of attacks on the international security force, Isaf.

And interim Defence Minister Mohammad Fahim survived an apparent assassination attempt which left four people dead and 50 injured last week.

There are also reports of a rocket attack on the residence of Kandahar governor, Gul Agha, and of heavy fighting leaving nine dead between rival warlords - one loyal to the interim adminstration - in the central Wardak province on Friday.

Returning king

King Zahir Shah is backed by interim leader Hamid Karzai, and is returning to inaugurate a Loya Jirga, or leadership council, in June, where a new government will be decided.

The fighting follows a recent attack on two British patrols in Kabul

But with violent ethnic rivalry and a high level of lawlessness entrenched in Afghanistan, there is concern that forces hostile to the interim administration are trying to destabilise the political process.

Our correspondent says this latest clash with al-Qaeda comes as British Royal Marines are about to declare that they are ready for combat operations in Afghanistan.

The bulk of the 1,700 British troops are currently undergoing last-minute training at Bagram airbase, outside Kabul.