The Conquest (Fatah) Alliance, the political arm of the multi-party Hashed, won around 15 seats in the October 10 vote, according to preliminary results.

In the last parliament it held 48, making it the second-largest bloc.

Several hundred Hashed supporters gathered on a Baghdad street leading to an entrance to the high-security Green Zone, home to the US embassy, other diplomatic missions and government offices, an AFP correspondent said.

"No to fraud, no to America," supporters chanted.

The Hashed demands the withdrawal of US forces from the country.

A 25-year-old man wearing a black Covid mask and sunglasses said he was protesting against electoral "fraud".

"The objective of the fraud is clear... it is the dissolution of the Hashed," he said, declining to be identified.

Hashed supporters have organised sporadic protests across the country in recent days.

On Sunday, they burnt tyres and blocked roads south and north of Baghdad.

Activists accuse the Hashed's armed forces -- whose 160,000 fighters are now integrated into Iraq's state security forces -- of being beholden to Iran and acting as an instrument of oppression against critics.

The big winner in the vote, with more than 70 spots in the 329-seat parliament according to the initial count, was the movement of Moqtada Sadr, a Shiite Muslim preacher who campaigned as a nationalist and critic of Iran.

Hashed leaders have rejected the results as a "scam" and said they will appeal, ahead of a final tally expected in the next few weeks.

On Saturday, several Shiite parties toughened their tone, accusing the electoral commission of not correcting "major violations" in the vote counting, and blaming it for "the failure of the electoral process", warning of negative repercussions on democracy.

The Hashed is still expected to carry weight in parliament through the cooptation of independent candidates and other alliances.