Gunmen killed a former Taliban leader who renounced the hard-line Islamic regime after it was ousted in late 2001 and had since supported Afghanistan's U.S.-backed government, witnesses said Saturday.

A suicide car bomb, meanwhile, wounded an American soldier when it blew up near a U.S.-Afghan military convoy traveling along a main southern Afghan road, a local police chief said.

In the southern city of Kandahar, two men on a motorbike fatally shot Mohammed Khaksar, the former Taliban deputy interior minister, as he walked with two of his children, said Mohammed Jan Khan, a student who witnessed the shooting.

He said the men shot Khaksar in the head and the heart and the victim collapsed on a road in the city, which was once a Taliban stronghold.

Khaksar's brother, Abdullah Jan, and the city police chief, Gen. Abdul Wahid, confirmed the killing.

Khaksar secretly contacted the United States in 1999 to seek American help in stopping the Taliban. He renounced the movement after it collapsed from a U.S.-led military offensive launched when the Taliban refused to hand over Usama bin Laden and close Al Qaeda training camps after the Sept. 11 terror attacks.

Last September, Khaksar ran as a candidate in legislative elections, but lost.

In an interview at the time with The Associated Press, Khaksar said Taliban holdouts who are waging an insurgency across parts of Afghanistan had threatened his life several times. He said he supported President Hamid Karzai, as well as the deployment of international troops here.

The suicide bombing occurred in Helmand province, which has suffered a spate of militant attacks recently, said Khan Mohammed, a district police chief.

The convoy of Afghan soldiers and U.S. military trainers was traveling on the main road from Kandahar to the western city of Herat.

The attacker was killed in the blast and his vehicle was blown into several pieces, Mohammed said. The bombing damaged one U.S. vehicle and slightly wounded one soldier, he said.

A U.S. military spokesman, Lt. Col. Jerry O'Hara, said initial reports suggested there had been an explosion, but said it was still being investigated.

It was the latest in a string of suicide bombings that represent a new security threat in Afghanistan, where there are worries that Afghan rebels are adopting the deadly tactics of insurgents in Iraq.

Karzai said in an interview with AP last week that he expected suicide attacks to continue "for a long time."

He said it was not clear who was behind them and suggested some of those responsible for about 20 suicide attacks over the past four months might have been duped into killing themselves.