A DOZEN small bombs exploded and mortar rounds landed near polling centres in Iraq yesterday, wounding at least four people during voting in the country's first provincial elections since the departure of US troops.

Two mortar rounds injured three voters and a policeman at a school used as a voting centre in Latifiya, south of Baghdad, soon after the start of the ballot that will measure parties' political strength before parliamentary elections in 2014.

Attacks have surged since the start of the year with a local al-Qaeda wing and Sunni Islamists stepping up their campaign to undermine the Shi'ite-led government and stoke confrontation among the country's combustible sectarian and ethnic mix.

Small bombs exploded in Tuz Khurmatu, Tikrit and Samarra in the north and six more mortar rounds landed in a town near the southern city of Hilla, without causing any injuries, said police.

Iraqi politics is deeply split along sectarian lines with Prime Minister Nouri al-Maliki's government mired in crisis over how to share power between majority Shi'ite Muslims, Sunnis and Kurds who run their own autonomous enclave.

For Maliki, a strong showing by his Shi'ite State of Law alliance may open the way for a shot at a third term in 2014 elections. He has hinted at plans, should he be successful, to abandon Iraq's unwieldy power-sharing deal to form a majority government.

Sunni rivals, deeply divided over how to work with Maliki's government and the premier's Shi'ite rivals – anti-US cleric Muqtada al-Sadr and the Islamic Supreme Council of Iraq movement – will look to chip away at Maliki's sway over provincial councils.

Security was tight across Iraq with more than 8000 hopefuls running for nearly 450 seats on provincial councils which select local governors. More than a dozen candidates, mostly Sunnis, were killed during campaigning.

Early turnout at polling stations in Baghdad, and cities like Basra, Tikrit and Baquba appeared light, according to reporters.

Many Iraqis are frustrated with insecurity, unemployment, rife corruption and the lack of basic services a decade after the invasion that ousted Saddam Hussein and helped trigger sectarian bloodshed that killed tens of thousands in 2006-07.