Ahmed Wali Karzai, the brother of the Afghan president and a suspected player in the country’s booming illegal opium trade, gets regular payments from the Central Intelligence Agency, and has for much of the past eight years, according to current and former American officials.

The agency pays Mr. Karzai for a variety of services, including helping to recruit an Afghan paramilitary force that operates at the C.I.A.’s direction in and around the southern city of Kandahar, Mr. Karzai’s home.

The relationship between Mr. Karzai and the C.I.A. is wide ranging, several American officials said. He helps the C.I.A. operate a paramilitary group, the Kandahar Strike Force, that is used for raids against suspected insurgents and terrorists. On at least one occasion, the strike force has been accused of mounting an unauthorized operation against an official of the Afghan government, the officials said.

Mr. Karzai is also paid for allowing the C.I.A. and American Special Operations troops to rent a large compound outside the city — the former home of Mullah Mohammed Omar, the Taliban’s founder. The same compound is also the base of the Kandahar Strike Force. “He’s our landlord,” a senior American official said, speaking on the condition of anonymity.