Here is a recap of four days of unrest, in which dozens of people have been killed and hundreds wounded.

- Spontaneous gatherings -

On October 1, more than 1,000 people take to the streets in Baghdad and several cities in southern Iraq to protest corruption, unemployment and poor public services.

It is the first large protest faced by Mahdi's fragile government nearly a year into its term.

Demonstrators gather in the capital's iconic Tahrir (Liberation) Square, in what seems to be a spontaneous movement, with no political or religious faction explicitly calling for protests.

Riot police disperse crowds with water cannon, tear gas and rubber bullets.

They also fire live ammunition when protesters regroup and appear intent on marching to the Green Zone housing government offices and foreign embassies.

Several people are killed.

Mahdi pays tribute to security forces, blaming the violence on "aggressors who... deliberately created casualties".

- Unrest spreads -

On October 2, protests multiply across southern Iraq, with thousands participating. In Baghdad, riot police attempt to disperse crowds in a half-dozen neighbourhoods by firing tear gas and live rounds.

Protesters try to reach Tahrir Square, but it is sealed off. They set fire to tyres and block main roads, while security forces seal off the Green Zone.

Riot police fire live rounds during demonstrations in the southern cities of Najaf and Nasiriyah.

More deaths and injuries are reported.

Liberal newspaper Al-Bayina Al-Jadida says the protests are "without flag, without poster or party slogan".

Firebrand Shiite cleric Moqtada Sadr later calls for "peaceful protests and a general strike".

Authorities impose a curfew in Baghdad and several other cities.

- Battles in Baghdad -

On October 3, major clashes occur as thousands of protesters defy the curfew to march in Baghdad and across the south.

In the capital, riot police and soldiers fire live rounds into the air and at the ground from automatic weapons mounted on military vehicles.

Crowds block streets and burn tyres in front of government offices in multiple cities, including Missan, Najaf, Basra, Wasit and Babylon.

Internet is cut to about 75 percent of the country, in what monitors say is a deliberate measure to prevent coverage of the unrest.

Amnesty International condemns as "outrageous" security force "brutality using lethal and unnecessary force".

In his first public address since protests began, Mahdi defends his government's achievements on television and asks for time to implement a reform agenda.

He describes the unrest as "the destruction of the state".

- Sistani's support -

On October 4, dozens of protesters wearing masks and carrying Iraqi flags gather in Baghdad from early in the morning, arriving in trucks and buses.

Large numbers of security forces are deployed to enforce the curfew, again blocking access to Tahrir Square

In a much-anticipated midday sermon, Iraq's revered Shiite spiritual leader Grand Ayatollah Ali Sistani endorses the protests and calls on the government to heed them "before it's too late."

The government "must do what it can to improve public services, find work for the unemployed, end clientelism, deal with the corruption issue and send those implicated in it to prison", Sistani says, listing some of the protesters' main grievances as the death toll since Tuesday reaches 36, including four police.

The UN calls on Iraq to rapidly and transparently investigate force used by riot police.