The curfew in Baghdad, which was imposed Thursday and slated to be lifted Sunday morning, has been extended for an indefinite period, state television Al-Iraqiya reported.
The extension comes as violent clashes continue between Shiite fighters and security forces in the capital and elsewhere, according to the report.
"The Baghdad military command has decided to extend the curfew in the Iraqi capital for an indefinite period," said the TV report.
Iraqi authorities imposed a curfew on Thursday in Baghdad, which was originally set from 11:00 p.m. (2000 GMT) Thursday to 5:00 a.m. (0200 GMT) Sunday.
The same rule has been implemented in six of the southern provinces, including Basra, according to Iraqi media.
Mortar and rocket fires, allegedly from Sadr City in the east of Baghdad, continued to hit some areas in the capital city during the day, including the Green Zone, which hosts Iraqi government facilities and the U.S. embassy.
At least one civilian was killed and three others injured.
Thousands of supporters of radical Shiite cleric Muqtada al-Sadr took to the streets Thursday, demanding the government stop attacking Sadr's Mahdi Army militia and release detained members.
Iraqi Prime Minister Nuri al-Maliki, however, vowed that the offensive will go on.