BAGHDAD -- A series of attacks north of Baghdad killed eight soldiers on Tuesday as Iraq's election campaign officially kicked off ahead of the April 30 nationwide vote.

Iraq is holding its first parliamentary elections since the U.S. troops' withdrawal in late 2011. Shiite, Sunni and Kurdish candidates are vying for 328 assembly seats in the deeply divided country, plagued by violence and corruption.

Prime Minister Nouri al-Maliki is eyeing a third term, even as he faces criticism by opponents who accuse him of failing to provide security and basic services to the nation.

The deadliest among Tuesday's attacks took place in the late dictator Saddam Hussein's hometown, Tikrit, 130 kilometres north of Baghdad.

A suicide bomber rammed his explosive-laden car into a convoy of army vehicles in the city, killing five soldiers and wounding 11, police officials said.

Hours later, gunmen sprayed an army checkpoint with bullets, killing two soldiers in the northern city of Mosul, the officials said. Elsewhere in Mosul, a gunman shot dead a soldier who was manning another checkpoint.

Medics confirmed the casualty figures. All officials spoke on condition of anonymity because they were not authorized to talk to the media.

Violence has escalated in Iraq over the past year, with 2013 seeing the country's highest death toll since the worst of the sectarian bloodletting began to subside in 2007. Iraqi security forces have been a favourite target for Sunni insurgents who want to undermine the Shiite-led government in Baghdad.

As the election campaign kicked off Tuesday, Iraqi towns and cities were flooded with posters of the candidates for parliament seats on main streets and intersections.

But the prolonged battle in the western Sunni-dominated Anbar province between Iraqi security forces and al-Qaida-inspired militants is likely to disrupt the election.

If the fighting goes on, Iraqi military officials say it would be impossible to hold elections inside the city of Fallujah, west of Baghdad, which has been taken over by the militants -- but they hint the vote could perhaps be held on the city's outskirts. As many as a third of the province's cities might be affected, election officials say.

The militants took control of Fallujah and parts of Ramadi in late December after security forces arrested a Sunni lawmaker sought on terrorism charges, then dismantled a year-old Sunni anti-government protest camp.