A string of bombings mostly in and around Baghdad on Wednesday killed 49 people and wounded 180 others, police said.
The attacks unfolded primarily in the Iraqi capital's Shiite areas, police said. Another occurred in Mosul, in northern Iraq.
The latest violence comes as Iraqi security forces have been conducting the Revenge for the Martyrs, an operation designed to track down al Qaeda members in and around Baghdad.
Jacqueline Badcock, the U.N. secretary-general's deputy special representative for Iraq, said, "no political goal or grievance can possibly justify this daily bloodshed of innocent civilians."
"This relentless wave of senseless killing has left thousands dead since April and reflects the merciless nature of its authors," she said.
Iraq has endured months of escalating violence stemming from decades-old discord between the nation's Sunnis and Shiites, the two largest branches of Islam.
Sunnis have felt politically marginalized under a Shiite-led government since the ouster of longtime leader Saddam Hussein in a 2003 U.S.-led invasion.
July was the deadliest month in Iraq in the past five years since the peak of sectarian violence in 2006 and 2007. According to the United Nations, 1,057 Iraqis were killed and another 2,326 were wounded in acts of terrorism and violence last month.