Car bombs have exploded across the Iraqi capital, Baghdad, killing at least 66 people.
Officials say more than a dozen attacks targeted mostly Shi'ite neighborhoods, including Sabi al-Boor, Bayaa and central Baghdad. Scores are wounded from the attacks.
No one has claimed responsibility for Monday's deadly violence, which comes as Iraq faces growing sectarian tensions after months of Sunni-led protests against the Shi'ite-run government.
Iraq's Sunni minority has accused the ruling Shi'ites of targeting them for arrests and marginalizing them politically.
Bombings and other violence have killed hundreds of people in Iraq this month.
Last week, U.S. Vice President Joe Biden telephoned Iraqi Prime Minister Nouri al-Maliki to express concern over the rise in violence.
The White House says Biden pledged continued U.S. support for Iraq in its fight against terrorism, and also spoke about the importance of outreach to leaders across the political spectrum.