At least 42 people have been killed in a bomb attack near a Sunni mosque, hours after Iraq's PM hailed a reduction in sectarian killings.
Iraqi and US troops have set up additional checkpoints in Baghdad
A truck bomb exploded as worshippers left the mosque in Habbaniyah, 50 miles west of Baghdad, police said.
As well as those killed, more than 60 people were hurt, reports said.
Earlier, Iraqi PM Nouri Maliki said sectarian killings and kidnappings had fallen in the wake of a new Baghdad security plan, launched 10 days ago.
Mr Maliki said 426 suspected militants had been held and almost the same number killed since 14 February.
VIOLENCE IN IRAQ
62,473 families displaced by sectarian conflict in last year (source: IOM)
At least 56,000 civilians killed since 2003 (source: IBC)
More than 3,400 coalition military deaths since March 2003
But on Saturday, at least seven people were killed and more than 30 injured in a series of attacks in the Iraqi capital.
And there were reports of 20 loud explosions in a southern district of the capital after night fell.
These were coalition air strikes targeting insurgents, said Iraqi officials quoted by news agency AFP. Another report, quoting an Iraqi brigadier, said the blasts were the result of "military operations".
Separately, the Iraqi interior ministry said Iraqi and US troops killed dozens of Sunni militants north of Baghdad.
After visiting the command centre co-ordinating the joint Iraqi-US security operation in Baghdad, Mr Maliki said 426 militants had been detained and "around that number" had been killed.
Mr Maliki vowed to deal even-handedly with both Shia and Sunni rebels
He said many more militants had left the capital and vowed to bring them to justice.
Mr Maliki stressed that the new plan - which had seen thousands of extra US and Iraqi troops sent to Baghdad - also depended on the co-operation of the people.
He said the indications were that Iraqis were willingly co-operating.
US military commanders have also spoken positively about the operation.
But they have said that the rebels are currently laying now, warning that higher levels of violence to will probably return.
In Habbaniyah, the local police said a truck which had stopped outside a Sunni mosque blew up as worshippers left an afternoon prayer service.
But the explosion was also close to a school and a police station and the precise target isn't yet clear.
Habbaniyah is in Iraq's western Anbar province, a Sunni stronghold where there have been frequent attacks on American forces.
The BBC's Jane Peel, in Baghdad, says a bombing like this is relatively rare.
However, the imam of the mosque has spoken out against the insurgents and al-Qaeda in the past, our correspondent says.
North of Baghdad, Iraqi soldiers - backed by US aircraft - raided a Sunni rebel base early on Saturday, Iraqi Interior Ministry spokesman Brig Abdul-Kareem Khalaf said.
He said dozens of suspected members of the Islamic Army in Iraq had been killed during the operation that lasted several hours.
The spokesman said he was unaware of any civilian deaths.
The US military said it had no report about the operation, the Associated Press news agency reported.