Iraqi Prime Minister Nuri al-Maliki won by far the most seats in parliamentary elections, results showed Monday, putting him in the driver's seat for a third term despite vocal opposition.

His State of Law alliance fell short of an overall majority, however, meaning Maliki will have to court rivals, some of whom have refused to countenance his bid for re-election.

Results from the election commission showed State of Law garnered 92 out of 328 parliamentary seats, with Maliki himself winning more than 721,000 personal votes.

Both were by far the highest such figures from the April 30 vote -- the first since US troops withdrew from Iraq at the end of 2011 -- and marked significant increases on his performance in the 2010 general election.

"I thank all the people who voted for us, and congratulate you on this great win," Maliki told supporters in televised remarks.

"All of this points to... a political majority," he said, referring to his efforts to rebuff so-called national unity governments made up of all the major parties.

Maliki's bloc won 30 seats in Baghdad alone, and came first in 10 out of 18 provinces overall, all of them in the premier's traditional heartland in the Shiite-majority south.

Celebratory gunfire could be heard inside the heavily fortified Green Zone, home to Maliki's official residence and the US and British embassies, and in central Baghdad.

It was seen as an indication of security forces' support for the premier.

His main rivals all finished with between 19 and 34 seats overall, according to an AFP tally of election commission results.

"This sets Maliki up for a third term," said Ayham Kamel, Middle East and North Africa Director at the Eurasia Group consultancy.

"It won't be without challenges, but... the results make me even more confident that Maliki is going to be prime minister again."

The results can still be challenged and could change before being finally certified by the supreme court.

- 'Testament to courage' -

Both the American embassy and the UN mission welcomed the result, with Washington calling it "a testament to the courage and resilience of the Iraqi people, and another milestone in the democratic development of Iraq".

Iraq's political parties have for weeks been meeting and manoeuvring as they seek to build post-election alliances, but forming a new government could still take months.

As in previous elections, the main blocs are expected to agree on an encompassing package that ensures the prime minister, president and parliament speaker are all selected together.

Under a de facto agreement, the prime minister is a Shiite Arab, the president is a Kurd and the speaker of parliament is a Sunni Arab.

After the 2010 election, it took nine months to form a government as parties engaged in protracted horse-trading and several blocs tried to oppose Maliki's re-election.

Voters often complain of poor electricity and sewerage services, rampant corruption, high unemployment and a litany of other concerns, but the month-long election campaign concentrated on Maliki's bid for a third term.

His critics accuse him of consolidating power, particularly within the security forces, blame him for a year-long deterioration in security and say the quality of life has not improved enough.

The election and its aftermath came amid a surge in violence that has killed more than 3,500 people this year, fuelling fears that Iraq could revert to the all-out conflict that cost tens of thousands of lives in 2006 and 2007.

In particular, the 63-year-old faces strong opposition in the Sunni-dominated west and the Kurdish north, with rivals there insisting they will not agree to a third term.

Maliki, who has been in charge since 2006, blames external factors such as the war in neighbouring Syria for the surge in unrest, and says his so-called partners in government snipe at him in public and block his efforts to pass legislation in parliament.

The run-up to the election was plagued by attacks on candidates and campaign rallies, as well as allegations of malpractice that apparently contributed to lower turnout in areas populated by disgruntled minority Sunnis.

More than 9,000 candidates stood for the 328 seats in parliament, with around 62 percent of eligible voters casting ballots.