Baghdad: Powerful Iraqi cleric Moqtada Al Sadr called for the "government of corruption" to be overthrown on Friday in the biggest show of opposition yet to Prime Minister Haider Al Abadi's authority.
Around 200,000 people rallied at the entrance to the heavily fortified Green Zone in central Baghdad, demanding reform, better services and an end to corruption in response to a call by Sadr.
Abadi promised political and economic reforms last summer after mass street protests, but quickly ran into legal challenges and systemic resistance to change.
Last month he vowed to appoint technocrats to replace ministers appointed on the basis of political affiliations but that pledge too remains unfulfilled and frustration with the government has increased.
"A chance should be given to efficient independent people, and those who took Iraq to the abyss should step aside," said Sadr, whose Al Ahrar bloc holds 34 seats in parliament and three cabinet posts.
Sadr's speech was broadcast on huge screens set up in the street and protesters waved Iraqi flags outside the entrance to the Green Zone, which was guarded by riot police standing behind razor wire.
Sadr, whose opinion holds sway over tens of thousands, including fighters who fought US troops in 2006-07, threatened to break into the Green Zone unless Abadi took action.
The Green Zone houses government buildings and foreign embassies including that of the United States and has also become a symbol of the isolation of Iraq's rulers from its citizens.
Baghdad-based political analyst Ahmed Younis said failure to root out corruption, and economic pressures due to slumping oil prices compounded by the battle against IS militant group had "pushed Abadi with the country to the edge of a cliff".
"Everybody is watching Abadi drag his feet in carrying out real reforms.... Moqtada Al Sadr is now trying to take the imitative and be the winner in the reform race".
After a 100,000-strong protest held by Sadr last week, Abadi said it was his critics that stood in the way: "The political blocs are still holding on to their ministers and by doing so we cannot reform the country," Abadi added.
Muhanad Al Gharrawi, an aide to Sadr and leader of the protests said: "Today we are here to call for major reform. We want a technocratic government that serves Iraq's interests. We won't accept a solution to be like morphine used only to tranquilize the anger of people."
Meanwhile, a UN team concluded this week after making the first assessment visit to Ramadi since its recapture from IS that "destruction in Ramadi is "staggering" and worse than anywhere else in Iraq.
It said the main hospital and train station had both been destroyed, along with thousands of other buildings. Local officials told the UN team 64 bridges and much of the electricity grid had been ruined.
Iraqi forces declared victory over the militant group in Ramadi in December and has since cleared most of the western Iraqi city. IS militants still hold pockets in the northern and eastern outskirts.
Its recovery boosted Abadi in his campaign to oust the militants from their northern stronghold of Mosul later this year.
But more than six months of fighting shattered most infrastructure and levelled many homes in Ramadi, the Anbar provincial capital where around half a million people once lived.
The fighting saw IS bomb attacks and devastating US-led coalition air strikes.
"The destruction the team has found in Ramadi is worse than any other part of Iraq. It is staggering," said Lise Grande, the United Nations' humanitarian coordinator in Iraq.
The two-day assessment found that nearly every building had been damaged or destroyed in frontline areas. In other districts, one in three or four buildings were damaged, it said.
UN analysis of satellite imagery last month showed nearly 5,700 buildings in Ramadi and its outskirts had been damaged since mid-2014, with almost 2,000 completely destroyed.
Grande said it was too early to say how much time and money it would take to rebuild.
The assessment team said the greatest concentration of such explosives was reported in south-central Ramadi.
The United Nations is working with local authorities on plans to rebuild health, water and energy infrastructure.
The UN team said a water plant in central Ramadi could probably be repaired quickly.
It said it had identified four potential relocation sites for returning civilians. Iraq's central government has yet to give the all-clear for the return of residents.