The protest follows similar demonstrations in the northeast province of Kunar following the deaths on Tuesday of the nine children who were killed while collecting firewood in the province's Dar-e-Pech district.

President Hamid Karzai angrily condemned the killings and US President Barack Obama and General David Petraeus, the commander of the US-led troops in Afghanistan, apologised for the incident.

"We don't want the invading forces," chanted one demonstrator carrying posters of the dead children. Another shouted: "Death to the government of President Hamid Karzai."

Civilian casualties are a sensitive issue in Afghanistan where US-led forces, currently numbering around 140,000 troops, are deployed against the Taliban who are waging an increasingly deadly insurgency.

Karzai says the deaths of civilians in military operations turn people against his pro-US administration. Civilian casualties have been a key source of tension between Kabul and its Western backers, the US and NATO.

The killing of the nine children in a helicopter raid had followed an insurgent rocket attack on a US-led military outpost in the mountainous region.

NATO's International Security Assistance Force said the children were mistaken for rebels responsible for the attack on the base. A week earlier, Karzai said the troops had killed 65 non-combatants during operations in Kunar province's Ghaziabad district.

That was followed by another incident in which Afghan authorities said troops killed six civilians in neighbouring Nangarhar province, also in an air raid.