Security personnel cast their ballots nationwide on Monday ahead of Iraq's first election since US troops withdrew, amid attacks on voting centers and fears the country is slipping into all-out conflict.

Soldiers and policemen lined up at schools across Baghdad and around the country as polling stations opened at 7 am, leaving with the traditional purple-ink-stained finger indicating they had voted.

Prime Minister Nuri al-Maliki, lambasted by critics for allegedly consolidating power and targeting minority groups amid a deterioration of security, is bidding for a third term in the April 30 polls, with Iraqis frustrated over poor basic services, rampant corruption and high unemployment.

The monthlong campaign has seen Baghdad and other cities plastered with posters and decked out in banners as candidates have taken to the streets, staged loud rallies and challenged each other in angry debates.

"I have come to vote for the sake of Iraq, and to change the faces who have not served Iraq," said Ahmed, a policeman wearing civilian clothes who was waiting in line at a polling station in central Baghdad and who declined to give his full name.

"We want to choose better people."

Along with more than 800,000 members of the security forces who are eligible to vote at more than 500 polling centers nationwide, hospital and prison staff, patients and inmates also voted on Monday.

The election commission, meanwhile, said that more than 60,000 ballots had so far been cast in out-of-country voting, which continued through Monday.

Attacks on candidates, election workers and political rallies have cast a shadow over the election, however, and parts of the country that have been out of government control for months will not see any ballots cast.

On Sunday alone, five voting centers in the northern city of Kirkuk were attacked by militants, while authorities have announced a week of public holidays to try to bolster security for the election.

The unrest is the latest in a monthslong surge in violence that has claimed nearly 3,000 lives already this year, while anti-government fighters have held control of an entire town a short drive from Baghdad since the beginning of the year.

List of grievances

Although voters have a long list of grievances, including poor electricity and sewage services, pervasive graft, difficulties securing jobs and near-daily violence, the election has centered around Maliki and his efforts to retain power.

His opponents, who span the communal spectrum, accuse him of shoring up his power base, while minority Sunnis in particular say the 63-year-old Shiite Arab discriminates against them.

Maliki contends that foreign interference is behind the deteriorating security, and he complains that he has been saddled with a unity government of groups that snipe at him in public and block his legislative efforts.

But according to analysts and diplomats, with a fractious and divided opposition and no clear replacement, he remains the front-runner in the first national election since 2010, and the first since US troops withdrew in December 2011.

Aziz Jabr, a political science professor at Baghdad's Mustansiriyah University, said the stakes were high for Maliki, warning that were he to lose his post, anger over decisions made during his eight years in power could compel his successor to seek retribution in court.

But, Jabr added, "the fissures that have emerged in the Shiite community in the past four years have not helped highlight another Shiite leader against Maliki."

Though not codified, Iraq's leaders have established a de facto agreement whereby the prime minister is a Shiite, the president a Kurd, and the speaker of parliament a Sunni Arab.

No single party is likely to win an absolute majority, however, and as in previous elections, coalition talks are expected to take months as the main positions of power are typically negotiated in one encompassing package.