At-a-glance: Ahmed Wali Karzai

Ahmed Wali Karzai, a younger half-brother of President Hamid Karzai, was a key powerbroker in the south and a controversial figure.

Ahmed Wali Karzai, a younger half-brother of President Hamid Karzai, was a controversial figure in Afghanistan, but was a key power-broker in the south.

The younger Karzai was gunned down on Tuesday in his own home, and the Taliban quickly claimed responsibility for the killing. A provincial police chief said he was shot dead by a long-serving senior bodyguard.

Ahmed Wali Karzai was the government's key powerbroker in the south, and his murder deprives NATO of a vital if controversial ally.

For seven years he headed the provincial council in Kandahar, where he was widely considered to control all commercial and political dealings. He was also reported to have been on the CIA's payroll.

The 49-year-old was a shadowy figure, dogged for years by allegations of unsavoury links to the lucrative opium trade and private security firms, but others said he brought control to an otherwise chaotic domain.

But despite his unsavoury reputation he played a crucial role for Americans in Kandahar, perhaps the toughest battlefield in 10 years of war and the focus of a troop surge last year.