Sunni rebels led by the Islamic State group have attacked a town north of Baghdad and seized local government buildings, police and witnesses said.

The fighters, in 50-60 vehicles, stormed the town of Dhuluiya, about 70km north of Baghdad early on Sunday, to take control the mayor's office, municipal council building and the police station. 

At least six people were killed in the fighting, including four policemen, two fighters, and two civilians.

The attack is the latest apparent gain for Sunni rebels after the Islamic State group launched an offensive last month to seized Mosul, Iraq's second city, and northern areas of othe country.

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They were pushed back at Dhuluiya on June 14 by soldiers loyal to the Shia-led government of Nouri al-Maliki, the prime minister, and Shia militiamen, but fighting has continued and they have taken other towns.

The police and witnesses said local police and tribes were battling the rebels in Dhuluiya on Sunday.

Rebels also bombed a bridge linking Dhuluiya to the nearby Shia town of Balad to the west.

Parliamentary election

Parliament meanwhile failed to agree a new prime minister, president and parliamentary speaker after the latest session was adjourned.

Many Kurdish MPs were unable to attend due to bad weather that disrupted flights in and out of Baghdad.

Kurdish leaders have in recent days refused to work with the government after Maliki said their capital, Erbil, was a haven for Islamic State fighters.

The latest adjournment of parliament came after the main Sunni bloc announced late on Saturday they would nominate its candidate for speaker.

Iraq's political elite is under pressure from the US, the UN and Iraq's own Shia clerics to reach agreement so politicans could deal with the rebellion and prevent the country fragmenting on sectarian and ethnic lines.

Maliki's opponents accuse him of ruling for the Shia majority at the expense of Sunni and Kurdish minorities, and want him to step aside, but he shows no sign of quitting.

His State of Law coalition is the biggest group in the Shia National Alliance bloc.

Source: Agencies