Afghan President Hamid Karzai's half-brother, Ahmad Wali Karzai, was assassinated at his home in Kandahar city Tuesday by a man identified as a member of his security team.

Afghan officials say Ahmad Wali Karzai — a powerful figure in the country's south — was shot and killed by his longtime friend, Sardar Mohammad, who was from the same village of Karz. They said Mohammad was meeting privately with Wali Karzai when he shot him in the head and chest, and was then killed by other members of the security team.

The Taliban claimed responsibility for the assassination. But Afghan officials said it is not clear whether Wali Karzai's killing was related to the insurgency or to an internal feud.

In Kabul, President Hamid Karzai told reporters the killing of his younger brother represents the suffering of all Afghan people. The Afghan leader traveled to Kandahar later in the day for the burial, set for Wednesday.

The commander of U.S. and NATO forces in Afghanistan, General David Petraeus, condemned Wali Karzai's murder and said NATO forces will support the Afghan government's efforts to bring those responsible to justice.

The Obama administration also condemned Wali Karzai's death “in the strongest possible terms.” White House spokesman Jay Carney said Tuesday the U.S. will work with Afghan authorities as they investigate the killing.

U.S. Secretary of State Hillary Clinton said she called President Karzai to extend her deepest condolences. She said that “for too long, the people of Afghanistan have suffered under the threat of violence, intolerance and extremism.” Clinton added that Washington remains committed to supporting the government and people of Afghanistan in their struggle for peace.

Also Tuesday, Italian defense officials said a roadside bomb killed an Italian soldier in western Farah province. Early Wednesday local time, NATO said two of its service members were killed in separate attacks in the south. A NATO statement said one soldier died in a bomb blast, while the other was killed in an insurgent attack.

In other violence, Afghanistan's spy agency said it foiled an attempt by a group of eight terrorists to kill Interior Minister Bismillah Mohammadi during his visit to eastern Paktia province.

A spokesman for the National Directorate of Security, Lutfullah Mashal, said three policemen and five insurgents were detained last week ahead of Mohammadi's visit. He said the policemen were stationed at Paktia's police headquarters and were in contact with a member of the Haqqani network based in Pakistan's tribal belt.

Afghan officials said the terrorists had provided the police officers with explosives, suicide vests and weapons.