A curfew is being imposed in Baghdad, Diyala and 10 southern Iraqi provinces ahead of the Shi'ite Muslim religious holiday, Ashura.
The 10-day long ritual, which has been a target of militants in the past, is expected to be attended by several million pilgrims.
State television in Iraq reports that all traffic will be banned from Thursday in the southern provinces. The curfew also covers Baghdad and the volatile province of Diyala, where earlier Wednesday, a female suicide bomber blew herself up in a crowded market, killing eight people.
Officials say several others were wounded in Wednesday's attack in a mainly Shi'ite town of Khan Bani Saad, near Baquba, capital of Diyala.
Separately, the U.S. military has announced that one of the key al-Qaida in Iraq leaders in Diyala, Abu Layla al-Suri, also known as Abu Abd al-Rahman, was killed in a military operation near Muqdadiyah, north of Baghdad last December.
The U.S. military this month launched an offensive in Diyala aimed at driving out al-Qaida in Iraq insurgents from the religiously mixed province.
Some information for this report was provided by AFP and Reuters.