Helicopter gunships were sent to the scene

An Afghan Government soldier was also injured in the clash at Shkin in Paktia province, near the border with Pakistan.

The Americans say at least 20 suspected Taleban members were involved.

"US forces estimate at least three enemy were killed in the exchange of fire," a statement from the American military said.

American reinforcements were sent to the scene, backed by fighter aircraft and helicopter gunships, but were unable to identify any targets.

There have been frequent rocket attacks on American bases in eastern Afghanistan, where remnants of the Taleban are believed to be active.

Taleban 'regrouping'

Afghan officials have reported an upsurge in activity by Taleban fighters who, they say, are attempting to regroup following their defeat by US-led forces.

Last month, two US special forces soldiers were killed and another wounded in an ambush in the south of Afghanistan said to have been carried out by Taleban members.

A US military spokesman said the number of battles between Afghan forces and suspected Taleban members had increased since Afghan President Hamid Karzai asked provincial governors to use their militias to eliminate Taleban forces in their territory.

"Over the past month or so, the governors of the various provinces have put more of their forces in the field," he said.

"Whenever you put more forces in the field, you increase the chance of more contact with the enemy."

Rumsfeld visit

About 11,500 US-led coalition troops are in Afghanistan, pursuing remnants of the former Taleban government and the al-Qaeda network of Osama Bin Laden.

The latest incident comes ahead of this weekend's planned trip to Afghanistan by US Defence Secretary Donald Rumsfeld.

Diplomats are reported as saying that Mr Rumsfeld's visit aims to reassure President Karzai that Washington remains committed to Afghanistan, in spite of engagements elsewhere.