A wave of bombings and shootings across Iraq killed 23 people on Monday as the country grappled with anti-government rallies and simmering political crises ahead of major Shiite commemoration rituals.

No group immediately claimed responsibility for the attacks in more than a dozen towns and cities that wounded 83 people, but Sunni militants such as Al-Qaeda's front group in Iraq regularly target officials and security forces in a bid to destabilise the government, and also often attack Shiite pilgrims.

The violence comes after anti-government protesters blocked a key highway to Syria and Jordan, amid political tensions between Shiite Prime Minister Nuri al-Maliki and a secular Sunni-backed party in his fragile national unity government.

Much of Monday's violence targeted Shiite pilgrims, ahead of Arbaeen commemoration ceremonies due this week.

In the deadliest attack, seven people -- three women, two children and two men -- were killed when three houses were blown up in the town of Mussayib, south of Baghdad, police and a medic said. Four others were wounded.

The victims were apparently targeted because they were Shiites, the officials said.

Shiite pilgrims embarking on the traditional walk to the holy shrine city of Karbala for Arbaeen commemorations were hit by three mortar strikes south of Baghdad that killed one worshipper and wounded nine others.

A series of attacks in restive Diyala province, north of Baghdad, wounded 19 people, including 10 Shiite pilgrims who were walking to Karbala.

Arbaeen marks 40 days after the Ashura anniversary commemorating the slaying of Imam Hussein, one of Shiite Islam's most revered figures, by the armies of the caliph Yazid in 680 AD.

Sunni militants often use the rituals as an opportunity to increase attacks against Shiites.

Attacks in Baghdad and north of the city, meanwhile, killed 13 people.

In the capital's central commercial district of Karrada, a car bomb detonated by a suicide attacker left at least four dead and 20 others wounded, security and medical officials said.

Authorities quickly cordoned off the scene of the blast and barred journalists from entering or taking photos and videos.

A series of bombings in the ethnically mixed northern city of Kirkuk and nearby towns killed five policemen and wounded 11 other people, local officials said.

And in the main northern city of Mosul, three policemen were shot dead in separate incidents, while one policeman was killed and another wounded by a roadside bomb in Tuz Khurmatu.

South of Baghdad, a car bombing outside government offices killed two people as the provincial governor was arriving.

"I saw a huge fire and heard a loud explosion," said Kadhim Jawad, who was at the scene of the attacks in the city of Hilla. "I saw shops near the explosion were badly damaged and there was a man lying on the street. He was covered in blood."

The blast also wounded 19 people, including a guard for the governor of Babil province and one of his photographers, a policeman and a medic said. The governor himself was unharmed.

The latest violence comes on the ninth consecutive day of anti-government protests in mostly-Sunni areas over alleged attacks against the minority community by the Shiite-led government.

The demonstrations were sparked by the arrest of at least nine guards of Finance Minister Rafa al-Essawi on charges of terrorism.

Essawi, a senior member of the Iraqiya bloc that is part of Maliki's unity government but frequently criticises him in public, has called for the premier to resign, further heightening tensions between the two sides.

Violence in Iraq is down from its peak in 2006 and 2007, but attacks still occur almost every day across the country.