Protesters storm parliament in Iraq's Green Zone

Jubilant supporters of Shiite cleric Moqtada al-Sadr invaded the main session hall, shouting slogans glorifying their leader and claiming that they had rooted out corruption.

The Iraqi capital was already on high alert for a major Shiite pilgrimage, participants in which were targeted in a bombing that killed 23 on Saturday, but extra security measures were taken after protesters stormed the Green Zone.

"You are not staying here! This is your last day in the Green Zone," shouted one protester as thousands broke in.

Besides the parliament compound, the restricted area in central Baghdad houses the presidential palace, the prime minister's office and several embassies, including those of the United States and Britain.

Protesters attached cables to the tops of heavy concrete blast walls that surround the Green Zone, pulling them down to create an opening, an AFP journalist said.

They then headed to parliament, where some rampaged through the building and broke into offices, while other protesters shouted "peacefully, peacefully" and tried to contain the destruction, another AFP reporter said.

Security forces were present but did not try to prevent the demonstrators from entering the parliament building, the reporter said.

Chaos in parliament

Protesters pulled barbed wire across a road leading to one of the exits of the Green Zone, effectively preventing some scared lawmakers from fleeing the chaos.

They also attacked and damaged several vehicles they believed belonged to lawmakers.

Inside the main hall where lawmakers failed to reach a quorum earlier in the day, protesters sat in the MPs' seats taking "selfies" and shouting slogans.

One protester called a friend on his mobile: "I am sitting in (parliament speaker) Salim al-Juburi's chair, I have a meeting, we'll talk later."

"We are the ones running this country now, the time of the corrupt is over," said another protester, as crowds filled rooms throughout the building.

Parliament failed to reach a quorum on Saturday after approving some of Prime Minister Haider al-Abadi's ministerial nominees earlier in the week.

The Green Zone unrest kicked off as Sadr ended a news conference in the holy Shiite city of Najaf during which he condemned the political deadlock.

He had threatened to have his supporters storm the Green Zone last month, but did not order them to enter the area in his Saturday address.

The politicians "refused to end corruption and refused to end quotas", Sadr said, adding that he and his supporters would not participate in "any political process in which there are any type... of political party quotas."

Key government posts have for years been shared out based on political and sectarian quotas, a practice demonstrators want to end.

Baghdad on high alert

Abadi's efforts to change the system have been opposed by powerful political parties that rely on control of ministries for patronage and funds.

According to officials in the interior ministry, the main entrances to Baghdad were temporarily closed.

Special security measures were also taken around sensitive sites in the capital, including the central bank and the international airport.

Security forces had already been on high alert across Baghdad as tens of thousands of Shiite faithful converged on the city for an annual commemoration.

Both Washington and the United Nations have warned that the political crisis could distract from the fight against the Islamic State (IS) jihadist group.

A car bomb that exploded earlier on Saturday in the Nahrawan area near Baghdad killed at least 23 people and wounded at least 38, security and medical officials said.

It struck a road used by pilgrims walking to the shrine of Imam Musa Kadhim in northern Baghdad, officials said.

IS, which considers Shiites to be heretics, claimed the attack and said it was carried out by a suicide bomber who detonated a vehicle laden with three tonnes of explosives.

Kadhim, the seventh of 12 imams revered in Shiite Islam, died in 799 AD. The pilgrimage has in recent years turned into a huge event that brings the capital to a standstill for days.

Iraqi forces backed by US-led military assistance have regained significant ground from IS, which overran large areas north and west of Baghdad in 2014.