His comments came as US and Iraqi troops stepped up patrols in Baghdad, causing huge traffic jams as the government formally launched a long-awaited security crackdown to stop the violence in the capital.

New checkpoints were set up in the city of six million of people and Iraqi troops randomly searched cars and passengers and forced cars to zigzag through soldiers' positions and barricades.

US President George Bush has committed 21,500 more Americans to the operation, which is expected to involve a total of 90,000 Iraqi and US soldiers.

Dozens of people left their buses to cross the central Sinak Bridge on foot rather than wait for the vehicles to move through the jams.

At one checkpoint, Iraqi troops stopped a convoy of three white SUVS that are commonly used by Iraqi government officials and checked their identification.

``We have started the new security plan. And we warn every one who runs against it. Now we are ready to impose law on all those who want to continue with rebellion,'' al-Maliki said during a meeting with officials in the Shiite holy city of Karbala.

``Baghdad operations started today under codename Imposing Law.''