Tens of thousands of flag-waving Iraqis have swarmed central Baghdad's wide boulevards demanding the root-and-branch downfall of the political elite in the biggest day of mass anti-government demonstrations since the fall of Saddam Hussein.

Key points: A woman was killed and at least 155 injured on Friday night in Baghdad, when tens of thousands of protesters hit the streets

A woman was killed and at least 155 injured on Friday night in Baghdad, when tens of thousands of protesters hit the streets The protests were peaceful through the day but turned violent at night, with police using tear gas and rubber bullets

The protests were peaceful through the day but turned violent at night, with police using tear gas and rubber bullets Dissenters are calling for sweeping change to the political system established after the 2003 US-led invasion and the widespread influence of Iran

The mass rally was a show of defiance against security forces that have killed at least 250 people since protests erupted a month ago.

Dissenters want sweeping change to the political system established after the 2003 US-led invasion and the widespread influence of Iran, which they blame for corruption, high unemployment and poor public services.

One woman was killed after she was struck in the head by a tear gas canister, Iraq's Human Rights Commission said, and at least 155 people were wounded on Friday as security forces used tear-gas grenades and rubber bullets on protesters camped out in the capital's Tahrir Square, Baghdad's biggest and most central plaza that has become the protest movement's epicentre.

Protests have accelerated dramatically in recent days, drawing huge crowds from across Iraq's sectarian and ethnic divides. ( Reuters: Ahmed Jadallah )

Five people died on Thursday night from similar injuries.

Protests have accelerated dramatically in recent days, drawing huge crowds from across Iraq's sectarian and ethnic divides to reject the political parties in power since 2003.

Friday, the Muslim main day of prayer, drew the biggest crowds yet, with many taking to the streets after worship.

Clashes have focused on the ramparts to the Republic Bridge leading across the Tigris River towards government buildings. ( Reuters: Thaier Al-Sudani )

By the afternoon, clouds of tear gas enveloped the sky as tens of thousands had packed the square, condemning elites they see as corrupt, beholden to foreign powers and responsible for daily privations.

Protests have been comparatively peaceful by day, becoming more violent and chaotic after dark as police battle self-proclaimed "revolutionary" youths.

One woman was killed after she was struck in the head by a tear-gas canister on Friday. ( Reuters: Khalid al-Mousily )

Clashes have focused on the ramparts to the Republic Bridge leading across the Tigris River to the heavily fortified Green Zone of government buildings, where the protesters say out-of-touch leaders are holed up in a walled-off bastion of privilege.

"Every time we smell death from your smoke, we yearn more to cross your republic's bridge," someone wrote on a nearby wall.

Amnesty International said on Thursday security forces were using "previously unseen", powerful tear-gas canisters modelled on military grenades that are 10 times as heavy as standard ones.

"We are peaceful yet they fire on us. What are we, Islamic State militants? I saw a man die. I took a tear gas canister to the face," said Barah, 21, whose face was wrapped in bandages.

US Secretary of State Mike Pompeo urged all sides to reject violence, adding that Iraq's official inquiry into the early October violence "lacked sufficient credibility".

Friday, the Muslim main day of prayer, drew the biggest crowds yet in the month-long protests. ( AP: Khalid Mohammed )

"The Iraqi people deserve genuine accountability and justice," Mr Pompeo said in a statement.

"The Government of Iraq should listen to the legitimate demands made by the Iraqi people."

Saddam Hussein-era building becomes symbolic anti-government landmark

The structure has sweeping views of protest hotspots such as Tahir Square and security force movements below. ( AP: Hadi Mizban )

A 14-storey, Saddam Hussein-era building on the Tigris River has emerged as a landmark in the anti-government protests gripping Iraq.

The structure has been abandoned since 2003, when it was bombed by the US-led forces in their invasion, but on October 25 it was taken over from security forces by thousands of demonstrators, who have sworn not to leave it.

Some sit on the edge, feet dangling in the air from high floors as they sway to blasting music with a clear view of Tahrir Square.

The building has a strategic location, with a bird's-eye view of Baghdad allowing the protesters to watch the security forces below.

A one-time commercial centre, the building was nicknamed the "Turkish Restaurant" because of a famous dining spot on the top floor that was a tourist attraction in the 1980s with panoramic views.

Thousands of people have staged a sit-in at a 14-storey, Saddam Hussein-era building on the Tigris River. ( AP: Hadi Mizban )

On Friday, protesters had set up checkpoints to redirect traffic in the streets leading into and surrounding the square, where thousands have been camped out.

A woman pushed her baby in a stroller draped with an Iraqi flag while representatives from several Iraqi tribes waved banners pledging support for the protesters.

Mohammed Najm, a jobless engineering graduate, said the square had become a model for the country he and his comrades hope to build: "We are cleaning streets, others bring us water, they bring us electricity, they wired it up.

"A mini-state. Health for free, tuk-tuks transporting for free," he said.

"The state has been around for 16 years and it failed to do what we did in seven days in Tahrir."

Despite Iraq's oil wealth, many live in poverty with limited access to clean water, electricity, health care or education.

From students to artists, activists to celebrities — thousands have gathered for the protests in Baghdad. ( Reuters: Ahmed Jadallah )

The Government of Prime Minister Adel Abdul Mahdi, in office for a year, has found no response to the protests.

'Civil conflict, chaos and destruction'

Iraqi forces have been criticised by human rights groups for firing live shots into the air as well as powerful military-grade tear gas. ( AP: Hadi Mizban )

In his weekly sermon, top Shi'ite cleric Grand Ayatollah Ali al-Sistani warned of "civil conflict, chaos and destruction" if the security forces or paramilitary groups crack down on the protests, giving an apparent nod to protesters who say the Government is being manipulated from abroad.

"No one person or group or side with an agenda, or any regional or international party, can infringe upon the will of Iraqis or force an opinion upon them," Ayatollah Sistani's representative said during a sermon in the holy city of Kerbala.

A powerful Iran-backed faction had considered abandoning Mr Abdul Mahdi this week, but decided to keep him in office after a secret meeting attended by a general from Iran's Revolutionary Guards.

An Iranian security official confirmed the general, Qassem Soleimani, had attended Wednesday's meeting to "give advice".

Dissenters want sweeping change to the political system established after the 2003 US-led invasion. ( Reuters: Thaier Al-Sudani )

Many see the political class as subservient to one or another of Baghdad's main allies, the United States and Iran, who use Iraq as a proxy in a struggle for regional influence.

"Iraqis have suffered at the hands of this evil bunch who came atop American tanks, and from Iran. Qassem Soleimani's people are now firing on the Iraqi people in cold blood," said protester Qassam al-Sikeeni.

Iraqi President Barham Salih said Mr Abdul Mahdi would resign if Parliament's main blocs agreed on a replacement.

Protesters say that would not be enough; they want to undo the entire post-Hussein political system which distributes power among sectarian parties.

"So what if Adel Abdul Mahdi resigns? What will happen? They will get someone worse," barber Amir, 26, said.

There were protests in other provinces, with the unrest having spread across much of the southern Shi'ite heartland.

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