More than 1,000 people were killed in violence across Iraq in May, according to the UN mission to the country.

The UN figures, released on Saturday, showed that 1,045 civilians and security personnel were killed last month, which surpasses the 712 killed in April, and making it the deadliest month recorded since June 2008.

“Iraqi political leaders must act immediately to stop this intolerable bloodshed,'' Martin Kobler, special representative of the UN secretary-general for Iraq, said, calling the death toll "a sad record".

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 imposed on Friday a sweeping ban on cars bearing common temporary licence plates across the Iraqi capital in an apparent effort to thwart car bombings.

Violence has increased sharply in Iraq over the past two months, with bombings in civilian areas growing more frequent as fears grow that widespread sectarian conflict may once again break out in the country.

Deadly crackdown

On April 23, a deadly crackdown by security forces on a Sunni Muslim protest in the northern town of Hawija, accelerated violence in the country.

Laith Kubba, a former adviser to Iraqi prime minister, told Al Jazeera that the conflict in neighbouring Syria risked further exacerbating domestic tensions inside Iraq.

Iraqi authorities believe al-Qaeda linked groups are responsible for much of the violence [AP]

Iraqi authorities should be united in their position on Syria rather than being divided by differing internal perspectives, he said.

"Under normal conditions, I think Iraq lives with a level of tension between its politicians," Kubba said.

"Bearing in mind what is happening in Syria, Iraq cannot afford all these [different attitudes to Syria], and it's going to be tough months ahead for Iraq as a whole, and certainly for the Iraqi government."

Tallies of Iraqi casualties have long been the subject of debate, and the UN total is considerably higher than that reported by news agencies in the country.

The Associated Press news agency counted at least 578 Iraqis killed in May, based on reports from Iraqi officials.

The UN 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 UN.

Surge in violence

Iraqi authorities believe the local offshoot of al-Qaeda and other Sunni-backed fighter groups are responsible for much of the violence.

But a series of attacks on Sunni mosques which left more than 100 dead in recent weeks is raising concerns that Shia fighters are also behind some of the violence.

Iraqis are growing increasingly concerned about the surge in violence.

"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."

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.