(CNN) -- A string of car bombings in predominantly Shiite neighborhoods across Baghdad on Monday killed 37 people and wounded 155, adding to rising concern about sectarian violence across Iraq.
According to police officials, 11 bombs exploded in busy areas of the city and its suburban districts, including three bombings in the predominantly Shiite Al-Shaab suburb.
After several years of relative stability in Iraq, violence has been on the upswing of late.
More than 5,000 civiilans have died and 12,000 have been wounded in terrorist attacks and other violence in Iraq in 2013, the United Nations Mission in Iraq reported this month. The region around Baghdad has been the hardest-hit, the agency said.
The violence suggests that "Iraq may be moving back to a level of civil conflict that will amount to a serious civil war," the Center for Strategic and International Studies warned in a recent report.
"There is also substantial reporting to show that Iraq's violence is not simply the product of extremists and terrorist groups," authors Anthony Cordesman and Sam Khazai said in the September 9 report.
"Iraq's growing violence is also the result of the fact that Iraq is the scene of an ongoing struggle to establish a new national identity: one that can bridge across the deep sectarian divisions between its Shi'ites and Sunnis as well as the ethnic divisions between its Arabs and its Kurds and other minorities," they wrote.
Last week, the office of the United Nations High Commissioner for Refugees said it was increasingly concerned that recent sectarian violence threatens to set off a new refugee crisis within the country.
About 5,000 people have been forced to flee the recent violence around Baghdad, heading largely for Anbar and Salah Al-Din governates, the agency siad.
The country is still struggling to deal with more than 1.3 million people who fled from one part of Iraq to another to escape earlier sectarian violence, the U.N. agency said.
CNN's John Defterios and journalist Aqeel Najam contributed to this report.