Iraq elections
Iraq's incumbent Prime Minister Nuri al-Maliki votes during the parliamentary election in BaghdadReuters

Amid simmering violence, Iraq is holding its first parliamentary elections since the pullout of American troops three years ago.

Prime Minister Nuri al-Maliki, who is seeking a third term, has been facing criticism for having failed to contain boiling sectarian tensions for his own political gains.

With nearly 20 million Iraqi citizens eligible to vote, no single party is expected to secure a decisive majority in the 382-seat parliament. A little more than 9,000 candidates are contesting the elections.

Polling stations opened at 07:00 local time (04:00 GMT) and will be closed at 19:00. Security has been beefed up across the country and the airspace has been closed.

A curfew is in place to prevent any untoward incident as the al-Qaida-linked Islamic State of Iraq and the Levant (ISIL) has vowed to disrupt the polls with suicide attacks and car bombs.

There are also concerns of low voter turnout due to the threat.

The country has been grappling with sectarian violence with the Shiite-dominated administration, led by Maliki, struggling to deal with Sunni Islamist extremists since the US troops' withdrawal in December 2011.

Caught between the watchful eyes of Iran in the eastern border and strife-torn Syria in the west, Iraq, on the brink of a fully-fledged civil war, is desperate to crawl out of instability.

The incumbent prime minister, who depicts himself as a Shiite guardian against violent Sunni militants, asked in his campaign: "Is ISIL and al-Qaida capable of reaching the target for which they were established ... bringing down Baghdad and the other provinces and destroying the holy shrines? ... I say no.

"ISIL is over, but its pockets still exist and we will keep chasing them and the few coming days will witness major developments."

The entire election campaign has been marred by violence and dozens of people have been killed.

According to UN figures, nearly 1,700 civilians have been killed during the first three months of 2014, one of the highest death tolls since the Iraq civil war in 2006-2007.