Soldiers moved into the sprawling slum in the early hours, securing most of the suburb in an operation that an army spokesman said had been coordinated with Sadr's movement to avoid bloodshed.

The operation, on the second anniversary of Prime Minister Nuri al-Maliki being sworn in, marked the first time since the US-led invasion of March 2003 that the Iraqi army had pushed so deeply into the area.

"The security forces have taken control of security for the city completely, God willing," Major-General Qassim Moussawi, a spokesman for the security forces in Baghdad, told a news briefing on "Operation Peace".

The operation marks the latest step by the government to extend control over areas of Iraq that were under the sway of Shi'ite militias or Sunni Arab insurgents.

Iraqi soldiers, who previously controlled only the outer perimeter of Sadr City, met no opposition during their advance into the suburb, home to two million people.

But Moussawi said soldiers had cleared more than 100 home-made roadside bombs before going in.

US military spokesman Lieutenant-Colonel Steven Stover said no American troops were involved in the operation which he said was Iraqi-planned and -executed.

Sadr City is the main stronghold of Sadr's Mehdi Army, a militia estimated to number tens of thousands that the US military once called the greatest threat to peace in Iraq.

Nampa-Reuters

World News Headlines Of The Last 48 Hours