Two car bombs exploded Monday as Shiite pilgrims traveled to Karbala to mark Arbaeen, the end of the 40-day mourning period for the Shiite martyr Imam Hussein.
Iraqi Prime Minister Nouri al-Maliki responded in a statement by saying attacks on Iraqi holy sites won't go unpunished, the Voices of Iraq news agency reports.
"The cowardly crimes, committed by terrorists and their supporters against the visitors of Imam Hussein's shrine won't pass without punishment and our armed forces and security bodies must continue their efforts till they (up)root the evil tree of terrorism," he was quoted as saying.
The bombing of the dome of the al-Askari Mosque in the Shiite holy city of Samara in February 2006 sparked widespread sectarian violence.
Though violence is down in general in Iraq, the country has witnessed an uptick in violence in 2011. Iraqiya, a Sunni-backed political coalition led by former Iraqi Prime Minister Iyad Allawi, condemned last week's attacks in Diyala and Salah ah-Din provinces.
"This attack illustrates the lack of security in the country and we call upon the government to truly participate in partnership and step up their security efforts as it is their duty to protect the lives of the citizens," Iraqiya declared in a statement.