Afghan and U.S.-led coalition forces killed nine militants after suspected Taliban fighters attacked two army checkpoints in the latest fighting to rock southern Afghanistan, an Afghan official said Friday.

Six militants were wounded in three hours of clashes but escaped, and one other militant was arrested, said Mohammed Zahir Khan, chief of Khas Uruzgan district in southern Uruzgan province, where the fighting erupted late Thursday.

Khan said none of the Afghan and coalition forces were hurt.

Over the past week, authorities received information that more than 200 Taliban were mobilizing in the district, and a search operation was under way to find them, he said.

The bodies of nine militants were recovered from the scene of the fighting, along with assault rifles, rocket-propelled grenades and hand grenades, Khan said.

Taliban followers have stepped up attacks in their former southern heartland, triggering the bloodiest fighting since a U.S.-led invasion ousted the hardline militia from power in late 2001. More than 700 people, mostly militants, have died since mid-May.

On Monday, more than 40 people died in a coalition airstrike in the Uruzgan capital of Tirin Kot. The coalition said the attack targeted a compound used by Taliban and the victims were militants, but residents say at least four civilians, including children, were killed.

Afghan President Hamid Karzai has ordered a probe into the incident.

Meanwhile, a suicide bomber was the sole victim in a failed attack Friday on an Afghan police convoy in the Gurbuz district of southeastern Khost province, bordering Pakistan, said provincial police chief Gen. Mohammed Ayoub.

The attacker, on foot, ran at a police truck driving slowly on a bumpy road and detonated his explosives short of the vehicle, Ayoub said.

There has been a spike in suicide bombings in Afghanistan in recent months as Taliban militants and allied extremists attempt to derail U.S.-backed reconstruction efforts in a country struggling to recover from a quarter-century of conflict.