Bombs targeting Shiite mourners in Baghdad killed at least 57 people on Saturday, while 12 died in other attacks -- the latest in the worst violence to hit Iraq since 2008. Despite major operations by security forces against militants and new restrictions on vehicles in the capital, Iraqi authorities have so far failed to curb the surge in unrest. 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. Officials 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. \"The perpetrators of this horrible crime are seeking to foment sectarian strife and instability,\" parliament speaker Osama al-Nujaifi, a Sunni, said in a statement on the bombings. Iraq has seen a number of sectarian attacks this year, raising fears of a return to the all-out Sunni-Shiite 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 and killed a local official. 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. In addition to major security problems, the Iraqi government has also failed to provide adequate basic services such as electricity and clean water, and corruption is widespread. And political squabbling has paralysed the government, which has passed almost no major legislation in years.