Suicide bombers attacked two checkpoints south of Baghdad onMonday, among a spate of attacks in central Iraq that killed 23 people as a generalelection looms next week.Iraq is going through a protracted surge in bloodshed that has killed more than2750 people so far this year and the UN envoy warned on Monday that militantswere seeking to stoke sectarian tensions between the Shiite Muslim majority and theSunni Arab minority.In the deadliest attack, a suicide bomber detonated a vehicle rigged with explosivesat a police checkpoint in the Suweirah area, south of Baghdad, killing 13 people andwounding 35, a police officer and a medical source said.Another suicide bomber blew up a vehicle at a checkpoint in Madain, killing at leasttwo people and wounding five, while gunmen shot dead one person and wounded atleast one other in Latifiyah, officials said.In the Sadr City area of north Baghdad, a car bomb in an area of shops killed fivepeople and wounded at least 12. A car bomb in the Shaab area killed at least twopeople and wounded at least nine.The attacks came a day after violence in Iraq, including a suicide bombing atBaghdad's Imam Kadhim University, killed at least 16 people.UN envoy Nickolay Mladenov condemned the attack on the university, which is runby the Shiite religious endowment, as an attempt to stoke sectarianism."This is yet another example of sectarian-based violence that the people of thiscountry need to fight in order to bring this country to tranquility, and it ishappening at a time when the Iraqi people are preparing to go to the polls in a fewdays," Mladenov said."The target has been selected to incite sectarian hatred."The April 30 vote is Iraq's first parliamentary election since US forces withdrew in2011 and is a major test for the security forces.While they were able to keep violence to a minimum during provincial elections lastyear, the security forces have failed to halt a surge of unrest this year.Violence has killed more than 500 people in Iraq so far this month, according to AFP figures based on security and medical sources.It has been fuelled by widespread anger among the Sunni Arab minority, who saythey are mistreated by the Shiite-led government and security forces.Militant groups have also been bolstered by the civil war in neighbouring Syria.