A suicide bomber has killed at least 15 people and wounded 29 near a mosque in a mainly Sunni part of the Iraqi capital Baghdad, security sources say. The attacker rode up on a motorcycle before setting off a bomb in the Adhamiya district.
The dead include Faruq al-Obeidi, a local leader of a US-backed Sunni militia fighting al-Qaeda in Iraq.
The BBC's correspondent in Baghdad notes that suicide bombings are still a daily occurrence in Iraq.
Mr Obeidi died on his way to hospital, reports say.
The bomber attacked as the militia leader sat with his bodyguards at a cafe and six guards died along with him, according to the Associated Press.
"I rushed to the scene of the explosion to see terrified people running everywhere, and women calling for their missing children," said witness Abu Mohammed, 54.
"The situation was chaotic and horrible. I saw dead bodies, wounded people and blood stains on the ground."
The bomber struck close to the Abu Hanifa mosque, one of the most important Sunni shrines in Iraq, just after the end of evening prayers.
Early reports gave Mr Obeidi's name as Faruq Abu Omar.
The militiamen, popularly known as the Sons of Iraq, are paid by US forces as members of "Awakening Councils" to protect neighbourhoods in areas where the local tribes have turned against al- Qaeda.
Awakening Councils have been credited with helping to reduce violence in Iraq and are a continual target for Sunni insurgents, the BBC's Crispin Thorold reports.