Iraqis turned out to vote on Sunday in their country's first free election in half a century, defying insurgents who launched deadly suicide bombings and heavy mortar strikes at polling stations.

By mid-day, at least 27 people were dead but the violence had slowed and voting picked up.

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In the most deadly attack, a suicide bomber blew himself up at a polling station in western Baghdad, killing himself, three policemen and a civilian, officials said.

In a second suicide attack at a polling station, a bomber blew up himself, one policeman and two Iraqi soldiers.

In a third suicide attack at a school in western Baghdad, three people and the bomber died, police said.

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And in a fourth, at another school in eastern Baghdad, a suicide bomber killed himself and at least three others. Another four people died in other suicide attacks.

Also, three people were killed when mortars landed near a polling station in Sadr City, the heart of Baghdad's Shiite Muslim community.

In addition, two people were killed when a mortar round hit a home in Amel, and a policeman died in a mortar attack on a polling station in Khan Al Mahawil, about 60 km south of Baghdad.

The heavy attacks started about 8:30am, less than two hours after voting began, in Baghdad and in other cities including Baquoba, Basra, Mosul and Samarra.

They eased around noon.

Casting his vote, interim Prime Minister Ayad Allawi called it "the first time the Iraqis will determine their destiny."