The aftermath of one of the bomb attacks in the Shaab district of Baghdad
A series of bombings outside mosques in the Iraqi capital Baghdad has killed at least 29 people, Iraqi police sources say.
More than 130 people were injured when the six apparently co-ordinated bombs struck five Shia mosques as worshippers were leaving after Friday prayers.
It was one of the deadliest attacks in recent weeks.
The UN Secretary General, Ban Ki-moon, condemned the attacks, saying targeting places of worship was unjustifiable.
MAJOR ATTACKS BEFORE AND AFTER US PULLBACK
31 July: At least 27 dead in string of bombs outside five mosques in Baghdad
9 July: 50 killed in bomb attacks Talafar (near Mosul), Baghdad, and elsewhere
30 June: US troops withdraw from Iraqi towns and cities. Car bomb in Kirkuk kills at least 27 people
29 June: Four US soldiers killed in combat in Baghdad
26 June: 13 killed, dozens hurt in bomb attack at Baghdad motorcycle market
24 June: 70 killed, 130 injured in marketplace blast in Sadr City, Baghdad
22 June: Wave of bomb attacks in Baghdad and elsewhere kills at least 29, wounds 75
20 June: At least 72 dead and 200 injured in lorry bombing outside mosque in Kirkuk
The bombings come exactly one month after the US troops pulled out from cities across Iraq, handing over security to Iraqi forces.
They also come just days after US defence secretary Robert Gates said, during a visit to Iraq, that the security situation there had improved "amazingly" in the past three years.
He said the US might be able to withdraw troops a little more quickly than planned.
The attacks took place within a short period of time at mosques in northern, eastern and south-eastern Baghdad.
The deadliest attack struck a mosque in the Shaab area of northern Baghdad, killing at least 23 people and wounding about 107.
At least four people died in almost simultaneous twin blasts near Rasoul mosque at Diyala bridge in the south of the city, while 17 were injured.
One died in Zafaraniya, while several more were hurt in the Kamaliya and Ilam areas of the city, reports said.
And in a separate attack in the northern city of Kirkuk, two people were killed when a car exploded in a market.
The UN's Mr Ban condemned the attacks.
"Attacks against places of worship cannot be justified by any political or religious cause," he said in a statement.
"These attacks appear to be aimed at provoking sectarian strife and undermining stability in Iraq."
In a joint statement, the US ambassador Christopher Hill and the top US commander in Iraq, Gen Ray Odierno, called the attacks "barbaric" and "criminal".
Following the Shaab explosion, bloodied prayer mats and discarded slippers could be seen on the ground outside the mosque.
Witnesses said worshippers had had suspicions about a parked car, and tried to warn local security forces, but were assured the vehicle was safe.
This was one of the deadliest attacks in recent weeks
The car exploded minutes later, and witnesses told AFP news agency that panicked local police began firing their guns randomly, inadvertently causing three of the deaths.
The explosions have strengthened Iraqis' concerns that their police forces are unable to offer adequate security now that US forces have withdrawn.
In the aftermath of the Shaab attack, AFP reported, local residents shouted abuse at police officers and later demanded they leave.
Nevertheless, Iraqi casualties in bomb attacks have dropped substantially since June, when 437 people died in the run-up to the US pullback of forces, AFP said - the deadliest toll in 11 months.
According to an AP tally, 306 people died in July.