Supporters of Shi'ite cleric Moqtada al-Sadr took to the streets of Baghdad on Sunday night to celebrate his lead in Iraq's parliamentary election. It marks a surprise comeback for the powerful Shi'ite cleric who had been sidelined by Iran-backed rivals.

Shi'ite militia leader Hadi al-Amiri's bloc, which is backed by Tehran, was in second place, according to the count of over 95 percent of the votes cast in 10 of Iraq's 18 provinces.

Prime Minister Haider al-Abadi appeared to be running third.

Security and commission sources had earlier said he was leading the election, which was held on Saturday and is the first since the defeat of Islamic State militants inside the country.

Turnout was 44.52 percent with 92 percent of votes counted, the Independent High Electoral Commission said - that was significantly lower than in previous elections. Full results are due to be officially announced on Monday.

Sadr and Amiri both came in first in four of the 10 provinces where votes were counted, but the cleric's bloc won significantly more votes in the capital Baghdad, which has the highest number of seats.

The commission did not announce how many seats each bloc had gained and said it would do so on Monday after announcing the results from the remaining provinces.

Abadi, a rare ally of both the United States and Iran, came in third in six provinces but ran fifth in Baghdad.

The results unexpectedly showed former Prime Minister Nuri al-Maliki, who was touted as a serious challenger to Abadi, lagging behind.