UPDATE 2: Explosions kills 24, at least 65 wounded in attacks, as polls open.
Explosions killed 24 people as Iraqis voted on Sunday in an election that Sunni Islamist militants have vowed to disrupt, in one of many challenges to efforts to stabilise Iraq before US troops leave.
Scores of mortar rounds, rockets and roadside bombs exploded near polling stations in Baghdad, and some elsewhere, in a coordinated campaign to wreck the voting for Iraq's second full-term parliament since the 2003 US-led invasion.
Iraq's political course will be decisive for President Barack Obama's plans to halve US troop levels over the next five months and withdraw entirely by end-2011. It will also be watched by oil companies planning to invest billions in Iraq.
In the deadliest attacks, 12 people died when a bomb blew up a Baghdad apartment block and four were killed in a similar explosion at another residential building. A Katyusha rocket killed four people elsewhere in the capital of seven million.
At least 65 people were wounded around the country.
The Baghdad security spokesman, Major General Qassim al-Moussawi, said most of the rockets and mortar bombs had been fired from mainly Sunni districts in and around the city.
"We are in a state of combat. We are operating in a battlefield and our warriors are expecting the worst," he said.
Despite the hail of attacks, Moussawi said a car ban aimed at foiling vehicle bombs had been lifted after less than four hours of voting. Curbs on buses and trucks stayed in force.
The Islamic State of Iraq, an al Qaeda affiliate, had warned Iraqis not to vote and vowed to attack those who defy them.
The 96,000 US troops still in Iraq stayed in the background, underscoring the waning American role in Iraq.
Voters in the ethnically and religiously divided country can pick between mainly Shi'ite Islamist parties that have dominated Iraq since Saddam Hussein's fall and their secular rivals.
Prime Minister Nuri al-Maliki, a Shi'ite, urged all parties to accept the election results. "He who wins today may lose tomorrow, and he who loses today may win tomorrow," he said after casting his ballot in the fortified Green Zone enclave.
One of Maliki's opponents, ex-Prime Minister Iyad Allawi, has already complained of irregularities in early voting.Allawi's secular list is tapping into exasperation with years of conflict, poor public services and corruption, and hopes to gain support from the once dominant Sunni minority.
About 6,200 candidates from 86 factions are vying for 325 parliamentary seats. No bloc is expected to win a majority, and it may take months to form a government, risking a vacuum that armed groups such as Iraq's al Qaeda offshoot might exploit.
Few elections in the Middle East have been as competitive as this one. Its conduct could determine how democracy in Iraq affects a region used to kings and presidents-for-life.
"Today is the day when Iraqis speak while others keep silent," declared Ammar al-Hakim, Shi'ite leader of the Supreme Islamic Iraqi Council (ISCI), after voting.
Maliki, whose State of Law coalition is claiming credit for improved security since sectarian warfare peaked in 2006-07, faces a challenge from ISCI and his other former Shi'ite allies, derided by Sunni militants as pawns of neighbouring Iran.
Anti-American Shi'ite cleric Moqtada al-Sadr, speaking at a rare news conference in Tehran, said holding an election under the "shadow of occupation" was illegitimate, but urged Iraqis to vote anyway to pave the way for "liberation" from US forces.
Sadr galvanised anti-US sentiment after the 2003 invasion but faded from the political scene after vanishing, ostensibly to embrace religious studies in Iran, more than two years ago. Sadr's Mehdi Army, once a feared militia, has stepped away from combat, but his political movement is seeking a comeback, running in harness with ISCI, its former Shi'ite rival.
In contrast to the previous election in 2005, Iraqis can vote for individual candidates this time, not just party lists.
"Democracy in Iraq is chaotic. Everyone lies," said Abdul Rasheed al-Tamimi, a labourer in the Shi'ite city of Najaf. "I'm only voting because it's an open list and I know the candidate personally. I can hold him to account if he breaks his pledges."
In Kirkuk, a city disputed by Kurds and Arabs, Bushra Qassim said she was voting to secure a better future for Iraq.
"This election is the last chance for Iraqis to change the reality in which they live so as not to repeat the terrorism that I and many other Iraqis suffered from," the 40-year-old said, her face deeply scarred from a 2008 car bombing that killed one of her sons and wounded her and three other sons.
Some of Maliki's rivals allege intimidation and arrests, adding to tensions created by a ban on 400 candidates accused of links to Saddam's outlawed Baath party -- a furore which exposed the lingering divide between Sunnis and Shi'ites.
In Anbar province, a Sunni bastion, tribal sheikh Ahmed Abu Risha said Sunnis were hoping the poll would make them feel they had a real stake in their now Shi'ite-dominated country.
"Change is our goal. We want to put fresh blood in the political process," said Abu Risha, leader of the so-called Awakening Councils which helped the US military push back a raging al Qaeda-inspired Sunni insurgency. (Reuters)