KANDAHAR, Afghanistan (Reuters) -- A suicide bomber on a motorbike has struck a convoy of foreign troops in southern Afghanistan, killing 12 civilians and wounding 30 people, a provincial governor's spokesman said.
Dawood Ahmadi, spokesman for the governor of Helmand Province, said the attack took place in the town of Gereshk, located on a major highway that passes through the province.
He could not say if any foreign troops from the International Security Assistance Force (ISAF) were hurt or killed.
Lieutenant Colonel Nick Richardson, spokesman for the British-led NATO contingent in the province, said: "We are aware of an incident which has taken place this afternoon in southern Afghanistan involving ISAF troops. Further information will be released when available."
Violence has been rising sharply in recent years as an insurgency gathers strength in southern and eastern Afghanistan, a trend the United States hopes to stem with a huge surge in troop numbers this year.
Helmand is one of the most violent provinces in Afghanistan, and the United States is sending more than 8,000 Marines there in coming weeks to double the size of the mainly British force.
Civilian deaths caused by both sides have also been rising, with public resentment at NATO-led air strikes becoming a major irritant in relations with Washington, and insurgent suicide bombings increasingly disrupting daily life.
Taliban militants have extended the size and scope of their activities and have carried out a number of attacks in major cities since last year, targeting government and other high-profile buildings as well as foreign forces.