Kabul - An Afghan policeman was killed after he shot dead a US soldier in eastern Afghanistan, while elsewhere in the country "friendly fire" killed a coalition soldier and an Afghan civilian was killed in a rocket attack, officials said Thursday.

The Afghan policeman opened fire from a tower and threw a hand grenade toward US military forces in Bermal district of south-eastern Paktika province on Thursday, killing a US soldier, the military said in a statement.

The soldiers, who were on patrol, returned fire and killed the attacker, it said.

In another incident also in eastern region, a US-led coalition soldier was killed and several others were wounded in a "friendly fire incident" on Thursday, the US military said in a separate statement.

The troops were responding to several small-arms attacks during a patrol, the statement said, adding that the incident happened when "Coalition forces called for mortar fire to eliminate the insurgents in the area."

The military was investigating Thursday's incidents, the statements said.

Earlier this year, Taliban militants claimed that one of their fighters entered a US military base and killed several US soldiers in Khost province. Afghan provincial officials said that the attacker was wearing a police uniform and killed a US soldier.

The second attack in a month against US military forces in the region by attackers in police uniform raises suspicions that Taliban militants could have infiltrated the police forces.

One Afghan civilian was killed and five others were wounded in a separate incident when an insurgent rocket attack hit a house in Lashkargah, the provincial capital for southern Helmand province, Daoud Ahmadi, spokesman for the provincial governor said.

He said a woman was also among those wounded in the rocket attack that was purportedly fired by Taliban militants and hit a civilian house in the city.

Lashkargah has been the scene of heavy clashes between Taliban militants and Afghan forces backed by NATO troops. The Afghan and NATO forces killed several militants, who had massed around the city for a "major attack" on the provincial capital earlier this week.

Afghan officials have claimed to have killed more than 200 militants including foreign fighters in the past five days in Helmand, which is also the largest opium producing province in the country.

More than 4,000 people - mostly insurgents but including more then 200 international troops and hundreds of Afghan forces - have been killed in Afghanistan conflict so far this year.

The Taliban-led attacks are on the rise despite the presence of around 70,000 in international forces deployed to the country from 40 nations. (dpa)