Around a million loyalists of cleric Moqtada al-Sadr rallied in south Iraq Monday decrying poor services and rampant graft on the ninth anniversary of the US-led invasion against Saddam Hussein.

Protesters flooded the centre of the southern port city of Basra for the rally, with demonstrators waving Iraqi flags and portraits of the anti-US Shiite cleric and his father, Grand Ayatollah Mohammed Mohammed Sadiq al-Sadr, killed in 1999 by assailants thought to have been sent by Saddam.

The demonstration came just days before Iraq is due to host an Arab League summit, the first meeting of the 22-nation body since Saddam's 1990 invasion of neighbouring Kuwait.

Reading remarks composed by Sadr, currently in Iran, Sadrist religious leader Sheikh Assad al-Nassari told the crowd: "We cannot rest when there is injustice against us."

"Demand your rights, I will support you, and with our unity we will be strong. You must fight for a stable nation."

Two officers in the police and army in Basra put the number of protesters at one million, while Sadrist officials claimed 1.5 million attended. An AFP journalist put the number of protesters at several hundred thousand.

Demonstrators, many of whom came from different provinces to take part in what was dubbed the "Day to Support Oppressed Iraqis", shouted: "Yes to rights! Yes to humanity! No to injustice! No to poverty! No to corruption!"

Some protesters held aloft electrical cables, water canisters and shovels to symbolise the poor services that plague Iraq. Others carried empty coffins with words plastered on them such as "democracy", "electricity," "education" and "services".

Despite increasing oil production, Iraq suffers from electricity shortages, with power cuts multiplying during the boiling summer, poor clean water provision, widespread corruption and high unemployment.

Sadr's movement, which counts around 40 MPs and several ministers as part of its political bloc, organised the demonstration to coincide with the ninth anniversary of the US-led invasion that overthrew Saddam.

The rally had no widespread anti-American message, though some protesters held aloft placards that read "No to America" and "No to Israel."

US forces, who numbered nearly 170,000 at their peak in Iraq, withdrew from the country in December, and now just 157 soldiers remain under the charge of the US embassy in addition to a marine detachment responsible for the diplomatic mission's security.

In recent years, the Sadrist movement had organised demonstrations on April 9, to coincide with the day the US officially ousted Saddam.