Supporters of prominent Iraqi Shiite cleric Moqtada al-Sadr take part in a sit-in protest in the streets, outside Baghdad's heavily fortified Green Zone, Iraq. (Thaier Al-Sudani/Reuters)

Thousands of followers of an influential Iraqi Shiite cleric took to the streets of Baghdad on Friday, pushing through security lines to cross a bridge on the Tigris River and get closer to the highly secure Green Zone, where the government is headquartered.

The show of strength by the cleric, Moqtada al-Sadr, follows his calls last month for government reforms. Sadr had refused to cancel the demonstration despite a statement from the Interior Ministry on Thursday that such a gathering was “unauthorized.”

The protesters pushed past security forces and checkpoints to move closer to the Green Zone, home to the country’s political elite and most of the foreign embassies in the city.

Bridges leading to the Green Zone were closed after the ministry’s announcement, but Sadr’s supporters cut coils of barbed wire and pushed aside barriers to cross the Jumhuriya Bridge.

“Today we cut the barbed wire, we opened the bridge and achieved victory,” said Fadil Hussein, 18, waving an Iraqi flag as helicopters buzzed overhead.

Hussein was among hundreds who surged across the bridge and to the walls of the Green Zone to begin setting up tents in anticipation of a prolonged sit-in.

Along with the war against the Islamic State, the Islamist group that has captured a third of Iraq, the government is also battling a crippling economic crisis.

Near-record-low oil prices have more than halved government revenue, and Iraqi officials predict a budget deficit of more than $30 billion this year. Many Iraqis blame their politicians for squandering the country’s fortunes when oil prices were high rather than investing in the country’s infrastructure, which is now crumbling.

Also Friday, pro-Sadr protesters pushed past barriers on a bridge farther up the Tigris, chanting, “With our souls and blood, we sacrifice for Iraq.” Despite the crowds and heavy security presence, no clashes were reported.

In February, Sadr demanded that Iraqi politicians be replaced by more technocrats and that the country’s powerful Shiite militias be incorporated into the Defense and Interior ministries. He also reiterated his threats to withdraw from Iraq’s political process if his demands are not met. Previously, Sadr has not followed through on such threats.

While Iraq’s political leadership has proposed multiple reform plans, progress has been slowed by a weak central government and increasingly sectarian politics.