baghdad - Bombs targeting Shiite mourners in Baghdad killed at least 57 people on Saturday, as another 12 people, among them 10 security forces members, died elsewhere in Iraq, officials said.

The attacks are the latest in a surge in violence this year that the authorities have so far failed to stem, the worst unrest to hit the country since 2008.

In the deadliest incident, two bombings struck near a funeral tent in Sadr City, a Shiite area of north Baghdad, at about 5:30 pm (1430 GMT), killing at least 57 people and wounding more than 120.

Sources said one of the blasts came when a suicide bomber detonated an explosives-rigged vehicle, while the other was either a bomb left under a car or a car bomb. Sunni militants including those linked to Al-Qaeda frequently target members of the Shiite majority, whom they consider apostates.

Iraq has seen a number of sectarian attacks this year, raising fears of a return to the all-out sectarian conflict that peaked in 2006-2007 and killed thousands of people. The Sadr City blasts came a day after two bombs exploded in a Sunni mosque north of Baghdad, killing 18 people.

The United Nations deputy special representative for Iraq, Gyorgy Busztin, had expressed “extreme concern” this week about sectarian-based displacement of Sunnis and members of the small Shabak minority, and the killing of Sunnis in the country’s south.

“The use of violence and intimidation against communities by illegal armed groups forcing them to flee their homes is unacceptable and a clear violation of basic human rights,” Busztin said.

Ten Iraqi security forces members — another frequent target of militants who oppose the government — also died in attacks on Saturday.

Five suicide bombers wearing SWAT uniforms attacked a police base in Baiji in the morning, while most of its forces were out on a mission, killing four police.

Police killed one of the bombers, who were on foot, but the others managed to detonate their explosives inside the base.

In the northern province of Nineveh, gunmen killed two prison guards, a soldier and one of the governor’s guards, while a roadside bomb killed two more soldiers.

And in Kirkuk province, also in north Iraq, gunmen kidnapped a local official, who was found after being shot dead. A soldier was kidnapped and killed in Kirkuk the day before.

Saturday was the deadliest day for Iraq since August 28, when attacks killed 75 people.

More than 540 people have now been killed so far this month and over 4,300 since the beginning of the year, according to AFP figures based on security and medical sources.