A powerful bomb tore through an armoured car near a disputed town north of Baghdad on Tuesday, killing two officials and badly wounding a third, weeks ahead of Iraq's first polls since 2010.
The blast, which also killed one of the officials' bodyguards and wounded another in the town of Tuz Khurmatu, brings to 11 the number of candidates in the provincial council elections who have been killed.
Mayor Shallah Abdul, council chief Abdulqader Naimi and Salaheddin provincial councillor Rashid Khorshid had been travelling together to inspect a road paving project north of the town when the bomb went off close to their armoured car.
Naimi and Khorshid, both candidates in provincial elections due to be held on 20 April, were killed, and Abdul was badly wounded and transported to a hospital in the Kurdish city of Sulaimaniyah.
The attack is likely to raise tensions in the town which is at the centre of a years-long row that politicians have warned threatens civil war.
A total of 11 election candidates have already been killed, according to an AFP tally, and authorities have already postponed the polls in two large provinces, throwing into doubt the credibility of the vote, Iraq's first since March 2010 parliamentary elections.
Tuz Khurmatu, home to about 110,000 Arabs, Kurds and Shiite Turkmen, lies 175 kilometres (110 miles) north of Baghdad at the centre of a tract of disputed territory claimed by both the mostly-Arab government in Baghdad and the autonomous Kurdish region.
The dispute is often cited by officials and diplomats as the biggest long-term threat to Iraq's stability.
The establishment in September of the federal Tigris Operations Command, which covers disputed northern territory, drew an angry response from Kurdish leaders and increased tensions with the federal government.
Then on 16 November, a firefight broke out during an attempt by Iraqi forces to arrest a Kurdish man in the town.
One person was killed and others were wounded, further worsening relations between Baghdad and Kurdistan as both sides deployed reinforcements.
The crisis, which Iraq's parliament speaker warned could lead to civil war, has since eased, but the dispute over territory remains unresolved.