Thousands of demonstrators stormed Iraq's parliament building in Baghdad to protest against the nomination for prime minister put forward by Iran-backed parties, the Wall Street Journal reported.
Protesters, according to state news agency INA, forced their way into the Green Zone after removing a number of concrete barriers.
No lawmakers were present in parliament when the protesters penetrated the area, which is home to government buildings and diplomatic missions.
Iraqi Prime Minister Mustafa Al-Kadhimi called on protesters to "immediately withdraw from the Green Zone."
He warned that security forces would seek "the protection of state institutions and foreign missions, and prevent any harm to security and order."
Reporting from Baghdad, Al Jazeera's Mahmoud Abdelwahed said the protesters wanted to convey the message "that they are against corruption, against corrupt politicians."
"They say the country has suffered many years of corruption and mismanagement… they say they will continue to protest peacefully here."
For his part, the leader of the Sadrist movement, Saleh Muhammad Al-Iraqi, said: "I stand in reverence and respect. It is a wonderful spontaneous and reformist popular message, thank you."
He added: "Your safety is more important than anything else. If you want to withdraw, I will respect this decision."
The Sadrist's bloc won 73 seats in Iraq's October 2021 election, making it the largest faction in the 329-seat parliament.
But since then, talks to form a new government have stalled and Al-Sadr has stepped down from the political process.
The Iraqi news agency reported that the protesters began to withdraw from the parliament following Al-Iraqi's speech.
On Monday, the Coordination Framework, a coalition of Shia parties close to Iran, nominated Mohammed Al-Sudani for the position of prime minister.
The Iraqi parliament is scheduled to hold a session within days to elect a new president from among 25 candidates. This move is necessary to assign a new prime minister.
Al-Sudani's nomination is expected to be approved by the parliament after the withdrawal of Al-Sadr's parliamentary bloc.
Al-Sudani is seen as being under the wing of former Iraqi Prime Minister Nouri Al-Maliki and helped found Al-Maliki's State of Law Coalition, through which he was elected to parliament three times. Al-Maliki has faced numerous corruption allegations.
For him to assume the job of prime minister, he would need 165 out of 329 votes in parliament.