BAGHDAD, Iraq (AP) -- An Iraqi army commander says U.S.-backed forces have launched an operation in Mosul against al Qaeda in Iraq

Maj. Gen. Riyadh Jalal Tawfiq, the commander of military operations in the northern city, issued a statement announcing the beginning of the offensive "Lion's Roar" against al Qaeda in Iraq on Saturday.

Mosul is considered the last important urban staging ground for al Qaeda in Iraq after it lost its strongholds in Baghdad and other areas last year.

"Operation Lion's Roar is an Iraqi led, planned and executed operation, and is another example of the Iraqis' growing confidence and ability to independently carry out complex combat, police and humanitarian operations," U.S. military spokeswoman Maj. Peggy Kageleiry said.

In Baghdad, disagreements over the details of an accord reached late Friday between Iraq's government and Shiite militants cast doubt on whether it would end the bloodshed in Baghdad's Sadr City neighborhood. The pact is to take effect today.

Under the terms announced by Shiite cleric Muqtada al-Sadr's lead negotiator, Sheik Salah Obeidi, Sadr's Mahdi Army militia would set aside their weapons and let the government pursue people wanted for attacks, provided that there is a warrant. In return, the government would stop what he called "random" raids and open blocked roads into Sadr City.

But Iraqi government spokesman Ali Dabbagh said, "The government has the right to raid and search any place that is suspected to contain heavy and medium weapons."