Militants of the Rabaa Allah group brandished mocking portraits of the prime minister, who is seen as pro-American, and other government officials showing their faces trampled underfoot.

Rabaa Allah is the newest and most powerful of a myriad of pro-Iran groups in Iraq.

It is seen by experts as a cover for Kataeb Hezbollah which has been integrated into the Iraqi security forces, giving it leeway to oppose the official line.

"We've brought out our men and our guns to send out a message of warning... to the American occupiers and the collaborating (Iraqi) government," a Rabaa Allah militant said in a statement read out at the rally.

On Tuesday, a government official announced that Baghdad has requested a "strategic dialogue" with US President Joe Biden's administration.

The two countries have yet to reach an accord on the 2,500 US troops stationed in Iraq.

The Iraqi parliament called for their withdrawal following a US drone strike near Baghdad airport in January 2020 that killed top Iranian military commander Qasem Soleimani.

Rabaa Allah militants have set fire to the offices of a television station and a Kurdish party, while also carrying out raids on alcohol stores.