BAGHDAD — The United Nations mission to Iraq said Saturday that more than 1,000 people were killed in violence across the country last month — the highest monthly death toll in years. Violence in Iraq increased sharply in April and May, with bombings in civilian areas growing more frequent and escalating fears that widespread sectarian conflict may once again break out in the country. The bloodshed accelerated after a deadly April 23 crackdown by security forces on a Sunni protest in the northern town of Hawija.

The U.N. figures showed that 1,045 civilians and security personnel were killed in May. That surpassed the 712 killed in April, the deadliest month recorded since June 2008.

U.N. envoy Martin Kobler called the figures "a sad record."

"Iraqi political leaders must act immediately to stop this intolerable bloodshed," he said in a statement.

More than half of those killed were in the greater Baghdad area. Car bombs and other explosives were responsible for the bulk of the casualties across the country.

Authorities on Friday imposed a sweeping ban on temporary license plates for cars across the Iraqi capital in an apparent effort to thwart car bombings. The temporary black plates are common in post-war Iraq, where for years it was difficult to obtain new ones. They are typically on older-model vehicles and are more difficult to trace, and authorities say they are frequently used in car bombings.

Many roads were also closed throughout Baghdad on Saturday.

The heightened security measures come as the Shiite faithful begin making an annual pilgrimage to the shrine of eighth-century Shiite saint Imam Moussa al-Kadhim in Baghdad. Pilgrims traditionally walk to the twin-domed shrine in Kazimiyah, where al-Kadhim is buried.

Tallies of Iraqi casualties have long been the subject of debate, and the U.N. total is considerably higher than that reported by news agencies in the country. The Associated Press counted at least 578 Iraqis killed in May, based on reports from Iraqi officials.

The U.N. says its totals are based on direct investigation and accounts from credible outside sources. They are conservative and may under-report the actual numbers of those killed, according to the U.N.

Iraqi authorities believe the local offshoot of al-Qaida and other Sunni-backed militant groups are responsible for much of the violence. But a series of attacks on Sunni mosques that have left more than 100 dead in recent weeks is raising concerns that Shiite militants are also behind some of the violence.

Iraq witnessed its deadliest bout of violence between 2006 and 2007, when the country was on the brink of civil war and armed men roamed the streets of Baghdad. At the peak of the sectarian bloodshed between Shiite and Sunnis, more than 3,000 were being killed every month.

While the killing remains far below levels seen last decade, Iraqis are growing increasingly concerned about the surge in unrest.

"People are now more cautious and more shops are closing earlier in my neighborhood," said Thabit Sultan Ahmed, 42, a teacher from the Sunni neighborhood of Saydiyah in western Baghdad. "The main obsession of all Iraqi people now is how to survive the violence, not about thinking about their rights or demands." (AP)