Iraqis defied a rash of attacks that killed seven people to vote Wednesday in the country's first general election since US troops withdrew, with premier Nuri al-Maliki proclaiming "certain" victory.

Queues formed from early morning at tightly-guarded polling stations despite a surge of violence in the runup targeting campaign gatherings and early voting by security personnel.

The stream of voters slowed later in the morning but the tempo was expected to pick up in the afternoon before polls close at 6:00 pm (1500 GMT).

Iraqis have a long list of grievances, from poor public services to rampant corruption and high unemployment, but the month-long campaign has centred on Maliki's bid for a third term and dramatically deteriorating security.

Maliki encouraged voters to turn out in large numbers and voiced confidence he would return to power after casting his ballot at a VIP polling centre in the Rasheed Hotel in Baghdad's heavily-fortified Green Zone.

"Today is a big success, and even better than the last elections, even though there is no foreign soldier on Iraqi soil," the premier said.

He called for a move away from national unity governments towards ones of political majority, and confidently told journalists: "Our victory is certain, but we are waiting to see the size of our victory."

The runup to the election, the first parliamentary poll since US forces departed in December 2011, has seen Baghdad and other major cities swamped in posters and bunting.

Parties have staged rallies and candidates have angrily debated on television, though appeals to voters have largely been made on sectarian, ethnic or tribal grounds rather than on political and social issues.

Analysts had voiced fears much of the electorate would stay at home rather than risk being targeted by militants, who killed nearly 90 people over the two previous days.

Fresh attacks were launched soon after polls opened on Wednesday morning, killing seven people and wounding 24.

Security officials reported more than 40 attacks in total, including mortar fire, roadside bombs and a suicide blast, all targeting polling stations or voters on their way to them in northern and western Iraq.

North of Baghdad, militants seized a polling station and blew it up, after expelling election staff and those waiting to vote.

But many Iraqis said they were determined to vote despite the unrest, voicing disdain for the current crop of elected officials.

- 'Change for my children' -

"I came to vote for change for my children and my grandchildren, to change the future and the situation of the country for the better," said Abu Ashraf, 67, a retired accountant who declined to give his full name.

"It is necessary to change most of the politicians because they have done nothing, and they spend years on private conflicts," he said after voting in west Baghdad.

Nearby, 19-year-old student Noor Raad said she had voted "to change the politicians, because most of them have not worked to improve the situation."

Others, however, voiced confidence in Maliki and his Shiite-led government.

"If we are not coming to vote, who is going to come (to power)?" asked Umm Jabbar, who had queued outside a polling station in the Shiite shrine city of Najaf since 6:00 am.

"Will the enemy come? I am voting for Maliki, because he is a thorn in the eyes of the enemy."

More than 750 people have been killed this month alone, as violence has hit its highest levels since a brutal sectarian conflict killed tens of thousands in 2006 and 2007.

Militants have controlled the town of Fallujah since the beginning of the year, preventing polling from being held in parts of mainly Sunni Arab Anbar province, west of Baghdad.

Maliki's critics have accused him of concentrating power and marginalising the Sunni minority, and say public services have not sufficiently improved during his eight-year rule.

The 63-year-old contends the violence is fuelled by the civil war in neighbouring Syria and has accused Sunni Saudi Arabia and Qatar of backing insurgents.

Maliki's State of Law alliance is tipped to win the most seats in parliament but fall short of a majority, meaning he will have to court other Shiite parties, as well as Sunni and Kurdish blocs if he is to return to power.

And although Maliki faces significant criticism, analysts say a fractious and divided opposition leaves him the frontrunner for the top job.