A political bloc led by populist cleric Moqtada al-Sadr, a long-time adversary of the United States who also opposes Iranian influence in Iraq, has won the country's parliamentary election, the electoral commission said on Saturday.

Mr Sadr himself cannot become prime minister as he did not run in the election, though his bloc's victory puts him in a position to have a strong say in negotiations. His Sairoon electoral list captured 54 parliamentary seats.

The Al-Fatih bloc led by Hadi al-Amiri, who has close ties with Iran and heads an umbrella group of paramilitaries that played a key role in defeating Islamic State, came in second with 47 seats.

The Victory Alliance, headed by incumbent Prime Minister Haider al-Abadi, took third place with 42.

The victory was a surprising change of fortunes. The cleric, who made his name leading two violent uprisings against US occupation troops, was sidelined for years by Iranian-backed rivals.