A double bombing in Baghdad has killed at least 14 people, including the head of a US-backed armed group which fights al-Qaeda in Sunni Muslim areas.
Riyadh Samarrai's wife mourned by his coffin at a mosque
Police say a suicide bomber struck at the entrance of the Sunni Endowment, or Waqf, office in Adhamiya district.
A second suicide attacker set off a car bomb a few metres away as people fled from the scene of the first explosion.
Riyadh Samarrai, leader of the Adhamiya Awakening group, also a Waqf employee, was killed along with his son.
The attacker is believed to be from among the more hardline Sunni insurgents who do not want reconciliation in Iraq, the BBC's Humphrey Hawksley reports.
Other bombs killed at least five people in Baghdad on Monday.
One of Mr Samarrai's bodyguards told reporters the suicide bomber had walked up to the former police colonel and embraced him before detonating his explosives.
At least 18 people were also injured in the twin attack.
Mr Samarrai's coffin was carried through the streets of Adhamiya to Iraq's most revered Sunni shrine, the Abu Hanifa mosque, as chanting mourners followed.
"The martyrdom of the colonel is an inspiration to us now," Abu Firas, another senior member of the Waqf, was quoted as saying by Reuters news agency.
"All of us will become Colonel Riyadhs."
US-backed "awakening councils", made up of insurgent fighters who turned against al-Qaeda extremists, have been credited with helping reduce violence across Iraq's Sunni Arab areas.
But correspondents say their offices and checkpoints are themselves becoming targets of pro-al-Qaeda bombers.
After the overthrow of Saddam Hussein it was a centre of anti-US resistance until the "awakenings" initiative in 2006 to counter al-Qaeda, which many Sunnis rejected for fomenting sectarian strife.