Iraqi National Security Adviser Muwafaq al-Rubay'i reported the failure at a news conference in the city today.
The news follows a period of relative calm after a U.S. commander there suspended offensive operations yesterday. Iraqi government forces are also operating in Al-Najaf.
Today, an estimated 10,000 Iraqis arrived in Al-Najaf from all around Iraq to demonstrate support for the insurgency led by Shi'a cleric, Muqtada al-Sadr.
Violence continued in other Iraqi towns. In Samarra, the U.S. military says it dropped a bomb that killed about 50 militants, but an Iraq police official says the death toll there was much lower.
South of Baghdad, in Al-Hillah, Iraqi police say they clashed with al-Sadr's militia. They report 40 militants were killed, along with three policemen.
The U.S. military also reports that a U.S. Marine and another soldier were killed in separate incidents in Al-Anbar Province, which includes the volatile Sunni cities of Al-Fallujah and Al-Ramadi.
(cpoompiled from wire reports)For the latest news on Iraq, see RFE/RL's webpage on "The New Iraq".