INFLUENTIAL Shiite cleric Muqtada al-Sadr's political coalition has won the most seats in Iraq's national parliamentary elections, according to complete results released by the country's electoral commission.

However, because he didn't stand as a candidate in the election, al-Sadr cannot become the country's prime minister.

The announcement comes nearly a week after Iraqis cast their votes and put Iraqi Prime Minister Haider al-Abadi in third place, according to seat allocations.

An alliance of candidates with close ties to mostly Iranian-backed paramilitary forces came in second.

After the results came through, al-Sadr said on Twitter: "Your vote is an honor for us. Iraq and reforms have won with your votes ... we will not disappoint you ... the blame, all the blame is on those who failed Iraq."

Al-Sadr's campaign focused on limiting Iranian influence in Iraq, and he is known for his opposition to the US following the 2003 invasion of the country.

Following the 2003 overthrow of Saddam Hussein, Al-Sadr led militant fighters who carried out deadly attacks on American forces and were notorious for sectarian killings of Sunni Muslims.

Turnout at the May 12 election was only 44.5 per cent - much lower than in previous polls.