Clashes between security forces and anti-government protesters in northern Iraq have left dozens killed, officials said.

The clashes broke out early on Tuesday morning when security forces entered an open area in Hawijah, west of Kirkuk, where demonstrations have been held since January.

Iraq's ministry of defence said, in a statement, that 20 armed men were killed along with three army personnel - one officer and two soldiers - in the violence.

The statement also said that the armed men used protesters as cover, and that the army has arrested 75 "fighters" and seized 40 rifles, plus grenades.

Sheikh Abdullah Sami al-Asi, a Sunni provincial official, said the fighting began when security forces entered the protest area in the town and tried to make arrests.

At least 10 worshippers were also killed when mortar rounds landed on an Iraqi Sunni mosque in Muqdadiya in Diyala province, 80km northeast of Baghdad, police and medical sources said.

Minister resigned

A Sunni member of the Iraqi cabinet resigned on Tuesday in protest after the security forces moved in against the mainly Sunni protesters.

"The minister of education, Mohammed Ali Tamim, resigned from his post after the Iraqi army forces broke into the area of the sit-in in Kirkuk" province, said an official from the office of Saleh al-Mutlak, the deputy prime minister.

"The resignation is final, and there will be no going back," the official added.

Tamim, who is a member of Mutlak's National Dialogue Front and is originally from Hawijah, was the third Sunni minister to resign since March, and the second to do so after deadly violence at a protest.

Agriculture minister Ezzedine al-Dawleh quit on March 8 after a protester was killed in northern Iraq, and finance minister Rafa al-Essawi, some of whose bodyguards were arrested on terrorism charges in December, announced his resignation at an anti-government demonstration on March 1.

'Vague law'

Tuesday's raid at the protest camp was reportedly aimed at Sunni rebels from a group known as the Naqshbandiya Army, and officials said security forces only opened fire after gunmen fired at them.

Protesters have taken to the streets in Sunni-majority areas for more than four months, calling for the resignation of prime minister Nouri al-Maliki and decrying the alleged targeting of their minority community by the Shia-led authorities.

Al Jazeera's Jane Arraf, reporting from Baghdad, said the protests "started in December sparked by the arrest of a major Sunni politician".

The demonstrations continue because "a lot of people are being arrested under a very vague and sweeping anti-terrorist law; a lot of these sweeps are happening in Sunni areas," she added. "They are also upset they have no jobs; a lot of Iraqis here were stripped of their jobs because they were affiliated with the former Ba'ath Party."