Taliban ambushed Tuesday foreign troops in the southern province of Kandahar, killing one civilian and injuring two in the crossfire, said a military statement.

Militants targeted vehicles of the NATO-led International Security Assistance Force (ISAF) with rocket-propelled grenades and small arms fire east of Kandahar city, according to an ISAF statement.

"Taliban extremists initiated this incident. They chose the time and location of the attack, deliberately putting the lives of civilians at risk," said Lt. Col. Mike Smith, spokesman for ISAF Regional Command South.

Foreign troops returned fire and moved out of the area, which was then secured by Afghan police. An investigation was launched into the latest in the series of civilian deaths in combat incidents in Afghanistan.

Nearly a quarter of more than 4,000 people killed in attacks in Afghanistan last year were civilians.

In an unrelated incident, a UN driver was shot dead by an inknown gunman in the southern Kandahar province.

"The motives for this attack need to be established, and we are working with the authorities in Kandahar to help the investigation," Tom Koenigs, the special representative for the UN secretary general for Afghanistan was quoted as saying by the statement.

"The safety and well-being of those Afghan and international staff who work for the UN in Afghanistan is a matter of paramount importance to us," Keonigs said, adding that the UN would spare no efforts to ensure that "Sadequllah's murderers are found and properly brought to account."