KABUL: Ahmed Wali Karzai, the Afghan president's assassinated younger brother, was either a drugs baron, a CIA agent or a fierce defender of the Afghan people, depending on who you listen to.

What is beyond dispute is that he was a controversial figure and a warlord who commanded tremendous power over Kandahar, one of the most restive provinces of the war-torn country and the spiritual home of the Taliban.

The son of a well-to-do political family from an influential Pashtun tribe, the Popalzai, he headed the provincial council in Kandahar for seven years, where he was widely considered to control all commercial and political dealings.

His powerful role necessitated regular talks with American forces waging a counterinsurgency in the key Taliban battleground.

But leaked cables released last year revealed true US feelings about the president's half-brother, who was long dogged by claims of unsavoury links with the lucrative opium trade and private security firms.

After one meeting with US envoy Frank Ruggiero in September 2009, the American diplomat said of Karzai, known by the acronym “AWK”: “While we must deal with AWK as the head of the provincial council, he is widely understood to be corrupt and a narcotics trafficker.”

He always flamboyantly denied the mass of allegations against him, including that he ran private militias and claimed he escaped an assassination attempt in 2009. He wasn't to be so lucky on Tuesday, when he was killed in his own home.

After the WikiLeaks debacle he told Tolo television: “Dear brother! First of all, I've no security company... If one is able to show one single contract under my name, I'll take all responsibility for all against myself.”

Kandahar is a make-or-break southern battleground in the US-led fight to defeat the insurgency, and the United States has thousands of troops in the area trying to wrest initiative from the Taliban and bolster the Afghan government.

The New York Times reported in 2009 that the younger Karzai had been on the CIA payroll for most of the previous eight years for services that included fielding recruits for an Afghan paramilitary operating under CIA direction.

The newspaper reported that he helped the CIA contact and sometimes meet Taliban followers. As with most allegations levelled against him in the Western press, Karzai wasted no time denying the report.

Aged 49 and the youngest of six boys and a girl, Wali Karzai shared the same father as his presidential brother Hamid but had a different mother.

He studied at one of Kabul's most prestigious schools, the Habibia High School, and after pro-communist forces took power in 1978 he went to live in Chicago, where he managed a branch of the family restaurant.

In the mid-1990s, he left behind two of his brothers in the United States to join his father and Hamid in Quetta, in southwestern Pakistan, where they were organising an anti-Soviet resistance.

Since the 2001 US-led invasion toppled the Taliban and installed Hamid as president, Wali Karzai “gradually built a powerful empire in Kandahar through the support of foreign backers and by bringing under his influence the province's key commercial, military and contracting networks,” wrote Carl Forsberg, author of a key report on the southern province.

But his influence and family ties to the key battleground divided opinion among residents and foreign forces fighting the war in the south.

“He was viewed by many as an obstacle to change and progress in the south -- by others as the most important figure in terms of bringing security,” said Candace Rondeaux, Afghanistan analyst for the International Crisis Group.

“He may have had more enemies than friends in the end,” she said.

Wali Karzai was a father of four. His youngest child, a boy, was born just three months ago, said a family member.