Iraq's security situation continues to worsen in the wake of the Obama administration's pullout of US forces.
A coordinated wave of bombings targeting Shiite Muslims killed at least 78 people on Thursday.
The attacks mark the second large-scale terror assault in Iraq since the US pullout was completed last month.
Coming one day before a Shiite holy day that draws hundreds of thousands of pilgrims from across the country, the attacks have raised fears of a deepening of a depending sectarian schism in the country.
The attacks, which began during Baghdad's morning rush hour, targeted Sadr City – the capital's largest Shiite neighborhood – and another district that contains a Shiite shrine, killing at least 30 people.
Hours later, a suicide attack hit pilgrims heading to the Shiite holy city of Karbala, killing 48.
The bombings in Baghdad and outside the southern city of Nasiriya are said to be the deadliest attacks Iraq has seen in over a year.
The Sunni-Shiite divide in Iraq has kept the country on the brink of civil war for years as their competing insurgencies in the country vie for power, but the US pullout and has brought the issue to a head.
Thursday's blasts occurred as Bagdhad's fledgling unity government, designed to include the country's main factions, is mired in political infighting between politicians from the Shiite majority and Sunni minority.
Under the dictatorship of Saddam Hussein the Sunni minority controlled Iraq.
Some Iraqis blame that political discord for the lethal strikes. However for several years Iraqi leaders have accused Saudi Arabia of backing the Sunni insurgency in the country as a means of contesting Persian Shiite Iran's influence.
US officials have long accused Iran of backing Shiite terrorists in Iraq as well.