An American soldier has been killed in clashes with enemy forces in eastern Afghanistan, US military officials have said.

The soldier's unit came under fire while on patrol at Shkin, in the province of Paktika, near the border with Pakistan.

It is the first time an American soldier has been killed on active duty in Afghanistan in the past seven months.

Two other US soldiers were injured in separate incidents in Afghanistan in the past 24 hours.

Gun battle

Eastern Afghanistan remains a dangerous area due to its porous border with Pakistan where many al-Qaeda are thought to be hiding.

The chairman of the US Joint Chiefs of Staff, General Richard Myers, said he did not think there had been an increase in al-Qaeda activity, but he said security in eastern Afghanistan would be a problem for some time to come.

In the latest attack, the US patrol came under fire at about 0400 local time (2330 GMT Friday), triggering a gun battle, Major Stephen Clutter told a military briefing at Bagram Air Base.

He said the wounded soldier was evacuated to a forward operating base in eastern Afghanistan, where he died during surgery.

US troops are still searching for Taleban and al-Qaeda fighters

The BBC's correspondent in Kabul, Kylie Morris, says the first death since May of a US serviceman in Afghanistan will come as a shock to the US military.

On Friday, a US soldier was injured when rockets landed inside a compound housing coalition forces, near Asadabad, in eastern Kunar province, Major Clutter said.

Another soldier was hurt by a rocket propelled grenade launcher during a training exercise near Spinboldak in south-east Afghanistan, the spokesman said.

Days earlier, two US special forces and their Afghan interpreter were hurt when a hand grenade was thrown at their jeep in Kabul - the first attack on American forces in the capital.

Fifteen US soldiers have been killed in hostilities since the beginning of the US led anti-terror campaign over a year ago in Afghanistan.

There are 8,000 American soldiers active in Afghanistan, where they continue to conduct searches for remnants of al-Qaeda and the Taleban, mainly in the country's east.

The commander of US forces in Afghanistan, Lieutenant-General Dan McNeil, said serving in Afghanistan was not a job without danger.