BAGHDAD (AP) — A suicide bomber assassinated a Sunni lawmaker in western Iraq on Tuesday, raising tensions in a part of the country that has been roiled by weeks of demonstrations. Seven people were killed in the attack.

While it was unclear who carried out the attack, the killing is likely to further strain relations between the central government and minority Sunnis who have been demanding reforms to policies they believe unfairly target their sect. Suicide bombings are frequently the work of Sunni extremists, such as al-Qaida, who seek to exacerbate Iraq's sectarian divide.

The governor of Anbar province, Qassim al-Fahdawi, said that lawmaker Ifan Saadoun al-Issawi was killed on his way to join one of the anti-government protests when a suicide bomber blew himself up in the restive city of Fallujah.

The attack comes two days after a convoy carrying Iraq's Sunni finance minister, Rafia al-Issawi, was struck by a bomb as he traveled to the city. Al-Issawi comes from the same tribe and is from the same political bloc as the lawmaker.

The parliamentarian was part of the Sunni-backed Iraqiya bloc, which holds some posts in Iraq's loose power-sharing government but is at the same time the main force in opposition to Prime Minister Nouri al-Maliki's administration.

He was also one of the main founders of Fallujah's branch of the Sahwa, a group of Sunni Arabs who joined forces with the U.S. military to fight al-Qaida at the height of Iraq's insurgency. Sahwa members have been frequent targets for Sunni insurgents, who consider them traitors.

Mohammed al-Khaldi, a member of parliament from the Iraqiya bloc, demanded an investigation into how the security breach happened.

"The situation in the country is tense, and this attack will complicate things here. A solution must be sorted out soon, and we demand that the government provide protection to the protesters in order to prevent further security breaches," he said.

According to police, the lawmaker was inspecting a roadwork project when his attacker, dressed as one of the construction workers, approached and pretended that he was trying to shake hands before blowing himself up.

Three of the lawmaker's bodyguards were killed in the blast, along with three laborers who were nearby, officials said.

Anbar province, which is dominated by Iraq's Sunni minority, has been the scene of more than three weeks of protests against the Shiite-led government.

They were sparked by the arrest of bodyguards assigned to Iraq's Sunni finance minister, the official whose convoy was struck Sunday. He escaped unharmed.

Mohammed Fathi, a spokesman for the Anbar provincial council, said officials have declared a three-day mourning period in the province.

The United Nations envoy to Iraq, Martin Kobler, condemned the attack. In a statement, he called on "all political forces to foil any attempt at instigating strife and to demonstrate utmost restraint."

In other violence, a car bomb went off in a commercial area in the city of Baqouba, killing two people and wounding five others, said police and hospital officials.

Baqouba is 60 kilometers (35 miles) northeast of Baghdad.

All officials spoke on condition of anonymity because they were not authorized to release details to journalists.

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Associated Press writers Sameer N. Yacoub and Adam Schreck contributed.