Wave of attacks rock Baghdad, targeting pilgrims on way to holy festival of Arbain.
A suicide bomber blew himself up amid a crowd of Shi'ite pilgrims south of Baghdad on Sunday, killing at least 40 people, police and medical officials told newswire AFP.
At least 60 people were also wounded in the blast in the town of Iskandiriyah, said Karim Al-Tamimi, a police lieutenant from the province of Babil.
"At around 3.00pm, when pilgrims were eating their lunch inside the tent, a bomber blew himself up amid the crowd," said Al-Tamimi.
Mohammed Al-Zaidi, of Babil province state health office, gave the same toll and said that at least 25 of those wounded were seriously injured.
A US military official confirmed the attack, but put the initial death toll at 25.
"The suicide bomber was wearing an explosives vest who detonated his explosives outside the Hateen Apartments, which is outside of Iskandiriyah," the official added.
The apartments are located on the route between the towns of Iskandiriyah and Musayyib in the region known as the "triangle of death".
The attack took place on a two-lane highway, the official said, adding that the casualties did not include any US military personnel.
The pilgrims were heading to Karbala to attend the Arbaeen ceremony which commemorates the 40 days following the killing in 680 of Imam Hussein, a grandson of the Prophet Mohammed, by armies of the Sunni caliph Yazid.
Groups of pilgrims marching to Karbala for the ceremony from across the country are often targeted by Sunni insurgents.
The US military official said about 42,000 pilgrims had travelled through the area on Sunday.
In other violence in Baghdad, three people were killed and 51 wounded in four attacks on Shi'ite pilgrims on the road towards Karbala, which goes through the restive Sunni neighbourhood of Dora, security and medical sources said.
One pilgrim was killed and 15 wounded when a roadside bomb detonated which was followed by shooting, a source at Al-Yarmuk hospital told AFP.
Two police officers were also wounded in the attack, the source added.
Separately, two pilgrims were killed and 18 wounded when insurgents tossed a grenade at a group of pilgrims after which shooting broke out, an Interior Ministry official said.
Ten people were wounded in a third incident, and four others in a fourth incident, all shot at a distance in the Dora neighborhood, hospital sources told AFP. Police were unable to say where the shooting was coming from.