BAGHDAD: Two bombs tore through a public square in the southern Iraqi city of Kut on Monday, killing at least 37 people in the worst in a string of bombings and suicide attacks across the country, officials said.

A roadside bomb exploded in Kut, a mainly Shia Muslim city 150 kilometres southeast of Baghdad, followed by a car bomb when security forces arrived on the scene, security officials said.

Dhiyauddin Jalil, a director of Wasit provincial health department, said at least 37 people were killed, and more than 68 were wounded in the blasts.

“Hospitals are still receiving casualties, but the situation is under control,” Khamis al-Saad, Iraq's deputy health minister, told Reuters.

Violence in Iraq has fallen sharply since the heights of sectarian slaughter in 2006-07.

But Sunni Muslim insurgents and Shia militants are increasingly targeting local security forces and government offices as the last American troops prepare to withdraw by the end of year.

Dozens more were killed on Monday in other bombings and attacks in other cities.

At least eight people were killed and 14 wounded when a suicide car bomber attacked a municipality building in the province of Diyala, two police sources said on Monday.

The attack happened in Khan Bani Saad, about 30 kilometres northeast of Baghdad.

Two suicide bombers attacked an Iraqi counter-terrorism unit in Tikrit, 150 kilometres north of Baghdad, killing at least two policemen and wounding six in a failed attempt to free al Qaeda prisoners, a police official said.

One attacker detonated his suicide vest hoping to kill a high-ranking counter-terrorism officer and the other was shot dead during the attack, said Captain Jassim al-Jibouri, an officer with the Tikrit counter terrorism unit.

In the southern holy Shia city of Najaf, at least three people were killed and 19 more wounded when two car bombs exploded, authorities said. Police captain Hadi al-Najafi in Najaf said the bombs targeted a police building.

Kut had been relatively quiet since August last year when a suicide bomber killed 30 policemen and destroyed a police station as the US military ended combat operations in Iraq.

More than eight years after the US invasion that toppled Saddam Hussein, US soldiers are scheduled to leave by the end of the year. But Iraqi and US officials are discussing whether some stay on as trainers after 2011.