BAGHDAD (AFP) - Iraqis voted on Saturday in the country's first polls since United States troops departed, a key test of its stability in the face of a spike in attacks that has claimed more than 100 lives.

But the credibility of the provincial elections has come into question, with attacks on candidates leaving 14 dead and a third of Iraq's provinces - all of them mainly Sunni Arab or Kurdish - not even voting due to security concerns and political disputes with the Shi'ite-led government.

Election day was marred by attacks that left three people dead and gunmen dressed in police uniforms who burned ballot boxes at one polling station, but far fewer people were killed than in the days preceding the polls.

The vote for provincial councils, responsible for naming governors who lead local reconstruction, administration and finances, is seen as a key gauge of Prime Minister Nuri al-Maliki's popularity ahead of a general election next year.

Turnout for the provincial vote was about 51 per cent, according to provisional figures from officials of the Independent High Electoral Commission. The count was expected to begin on Sunday.

"Today is a day of change," Mr Salah Hussein, a 45-year-old government employee, said after voting, expressing hope that persistent failings in public services would be addressed.

"Security is the most important problem that all of them should be working for - without this, life would be so difficult," student Abdulsahib Ali Abdulsahib, 22, said after he cast his ballot.

Security on Saturday was tight, with voters searched before entering polling stations and numerous extra checkpoints set up by soldiers and police in Baghdad.

For most of the day, only approved vehicles were allowed on the streets, which were largely deserted except for security forces, and groups of children who took the opportunity to play football.

Despite heightened security in Baghdad and elsewhere, militants were still able to carry out attacks, although the death toll was much lower than the preceding six days, when an average of 20 people were killed daily.

Nine mortar rounds, four bombings and five stun grenades, all outside Baghdad, left three people dead and two wounded, officials said.

And gunmen dressed in police uniforms entered a polling station near Baquba, north of Baghdad, burned boxes of ballots and then escaped.

Every Iraqi who votes "is saying to the enemies of the political process that we are not going back," Prime Minister Nuri al-Maliki said on state television after casting his ballot at the Rasheed Hotel in Baghdad's heavily fortified Green Zone.

"I say to all those who are afraid for the future of Iraq and afraid of a return of violence and dictatorship that we will fight by casting ballots," Mr Maliki said.

The elections, which came a decade after US-led forces ousted now-executed dictator Saddam Hussein, were the first since parliamentary polls in March 2010, and the first time Iraqi forces secured elections without support from American or other international forces since 2003.

An estimated 13.8 million Iraqis were eligible to vote for more than 8,000 candidates, with 378 seats being contested.

"Elections do not solve every problem in Iraq, but no problem can be solved without elections," UN special envoy Martin Kobler told journalists after touring a polling station in central Baghdad.

Major issues affecting voters such as poor public services and rampant corruption have largely been ignored during the campaign, however, and the lead-up to the vote was blighted by a rise in violence that left more than 100 people dead in the past week.

Six of Iraq's 18 provinces also did not participate - two because authorities say security cannot be ensured, and four because of political disagreements.