A car bomb has exploded near the Iraqi town of Baquba, killing at least nine people and wounding dozens more.
The blast was the deadliest since the new government took office
Witnesses say the bomber targeted mourners at a memorial service for two Iraqi men shot dead on Sunday.
Two brothers of one of the men being mourned were reportedly killed in the attack - the worst since the interim Iraqi government took over on 28 June.
The blast comes as the government prepares to reveal new laws aimed at tackling the insurgency.
The unveiling of the new security legislation has already been delayed at least twice.
This has prompted critics to accuse the government of incompetence - though Iraqi officials say more time was needed to balance tougher curbs on the resistance with human rights concerns.
A US army official said no US troops were in the area at the time of the car-bomb attack on the funeral, which, he said, "was clearly aimed at innocent Iraqis".
It appears bombers may specifically have tried to target a local administrative chief.
US forces arrived later to calm angry crowds at the blast scene in Khalis, near Baquba.
A witness told the Reuters news agency the bomber "drove right into the funeral gathering and his car exploded".
One police chief was quoted as saying 14 people died and 70 were injured in the attack, though this has not been confirmed. Security sources said a senior police commander was among the wounded.
A family was left grieving for the second time in days, reported the AFP news agency.
It spoke to members of the Khadran family, who were holding the memorial outside their home after one son was killed in an earlier attack on Sunday.
Two brothers of the man died in Tuesday's assault. Another brother, Uday Adnan Kadran, 44 - the administrative chief of Khalis - was wounded in the attack.
"If they just wanted to kill Uday, they could do that easily as he drives his own car and has no bodyguards, but I think the whole family is a target," his cousin Aqil Hussein told AFP.
"We have hurt no-one and things are getting better. What is our fault if the old regime is gone?"
Guerrillas have regularly targeted Iraqi politicians and security forces, whom they accuse of collaborating with the US military occupation.
Baquba lies 60 kilometres (35 miles) from Baghdad and has been a hotbed of resistance to US forces and the Iraqi security corps trained by them.
Insurgents tried to take government buildings and police stations only days before power was handed over to Iraqis.
In other developments:
The US military announced the deaths of four more marines from the 1st Marine Expeditionary Force conducting operations in Anbar province, western Iraq. Three marines died after an encounter in the same area on Monday.
A roadside explosion aimed at a convoy of security guards killed a civilian and injured two others in the southern city of Basra.
US troops fired on a car that failed to stop at a checkpoint in Baghdad, killing one child, the US military said.
Two Iraqi police officers were seriously hurt after gunfire hit their car in Latifiyah, south of Baghdad.