Violence between Sunnis and Shiites in Iraq has corresponded with political tensions that erupted after U.S. combat forces left Iraq in 2011. At least 57 people died and 190 others were wounded in attacks across the country Monday and eight people died in sectarian violence Tuesday.
State Department spokesman Patrick Ventrell said the U.S. government was "deeply concerned" by the escalation of violence in post-war Iraq.
"U.S. officials in Baghdad and Washington are intensively engaged," he said. "We're in contact with a wide range of senior Iraqi leaders to urge calm and help resolve ongoing political and sectarian tensions."
U.N. special envoy for Iraq Martin Kobler called on Iraqi leaders to work together to prevent the country from sliding into "a dangerous unknown."
Kobler announced last week that provincial elections in Anbar and Ninaveh were scheduled for June 20. Both provinces were left out of April elections because of the violence.
Sunni tribal forces in Anbar raided a police headquarters in Ramadi in response to a security raid in the region in early May. Anbar was home to the insurgency that raged during the height of the war.