TIKRIT - Suicide bombers and gunmen killed at least 54 people in Iraq on Monday, medical and police sources said.

In Baiji, 180 km north of Baghdad, four men wearing explosive belts took over a police station after detonating a car bomb parked outside, police sources said.

Two blew themselves up inside the station, killing five policemen. The other two did the same about an hour later as Iraqi special forces counter-attacked, the sources said. “We believe the attack was aimed at freeing detainees who are being held in the building next door,” said Major Salih al-Qaisi, a police officer at the scene. “All the militants were killed before they reached the police department building where the detainees are held.”

No group immediately claimed responsibility for the attack, but suicide bombings are the trademark of al Qaeda’s Iraqi wing, which merged this year with its Syrian counterpart to form the Islamic State of Iraq and the Levant (ISIL).

Two hours later, three suicide bombers seized the local council building in Tikrit, 150 km (95 miles) north of the capital, after setting off two car bombs outside, security sources said. At least three people were killed.

Iraqi security forces surrounded the building, and then carried out an assault that Counter-Terrorism Service spokesman Sabah Noori said freed 40 people who were held inside. “We freed all the hostages... and our forces killed one suicide (bomber), but two others blew themselves up,” Noori told AFP.

A police major and a doctor meanwhile said that a city council member and two police were killed, though it was unclear whether they died during the initial attack or the later assault by security forces.

Following the initial attack by the militants, security forces had ordered all government employees in the city, including teachers, to go home for the day.

The deadliest single attack on Monday was in the northern city of Mosul, where militants gunned down 12 people on a bus. The city has become one of the most dangerous parts of Iraq, with militants carrying out frequent attacks and reportedly extorting money from shopkeepers.

Also on Monday, five car bombs and a magnetic “sticky bomb” on a vehicle exploded in and around the Iraqi capital, killing at least 17 people and wounding at least 43 - the second series of blasts in the area in 24 hours.

One of the car bombs went off in a car park near the Baghdad provincial council headquarters, killing at least four people and wounding at least 11.

The attacks came after another series of bombings in and around Baghdad killed at least nine people on Monday night, while violence elsewhere in the country that day killed a further 11 people, among them a TV presenter and a family of five. The presenter, Nawras al-Nuaimi, was the sixth journalist to be killed in Iraq since October, five of whom died in Mosul.

Iraq has come in for repeated criticism over shortcomings in media freedom, and ranks first in the Committee to Protect Journalists’ Impunity Index, which tracks unsolved murders of journalists.

More people died in violence in the first eight days of this month than in the whole of last December, and over 6,500 people have been killed since the beginning of 2013, according to AFP figures based on security and medical sources.

Officials have blamed the violence on Al-Qaeda-linked militants emboldened by the civil war in neighbouring Syria, but analysts and diplomats also say the government has not done enough to address underlying domestic grievances fuelling the violence.