Shi'ite radical cleric Moqtada al-Sadr has called for a political solution to the crisis that has led to fierce fighting between his followers and Iraqi forces in Baghdad and southern Iraq.
In a statement released Thursday in the holy Shi'ite city of Najaf, Sadr said he wants everyone to pursue political solutions and peaceful protests and a stop to the shedding of Iraqi blood.
However, Iraqi Prime Minister Nouri al-Maliki vowed to continue the military offensive in Basra "to the end" with no negotiations or retreat.
Shortly afterwards, Iraqi authorities imposed a three-day curfew in Baghdad in a bid to contain violent clashes that have left more than 100 people dead.
Under the curfew, which will last until 5 a.m. Sunday, no unauthorized vehicles or pedestrians are allowed on the streets.
On Wednesday, Mr. Maliki issued an ultimatum, ordering Shi'ite gunmen to surrender their weapons by Friday or face the consequences.
Suspected Shi'ite extremists also continued to attack Baghdad's heavily fortified Green Zone Thursday, killing one civilian and wounding 14 others.
The US State Department instructed all personnel at the American embassy in Baghdad not to leave reinforced buildings following insurgent attacks that have killed two Americans this week.