BAGHDAD - At least 36 people were killed and dozens wounded when more than 20 car and roadside bombs, mostly targeting security forces, exploded around Iraq on Thursday, police and hospital sources said.The biggest attack took place in the northern oil city of Kirkuk, where two car bombs aimed at city center police patrols killed four people and wounded 24, police and hospital sources said."I was trying to stop traffic to let a police patrol pass. When it passed, a car bomb exploded and I fell on the ground and police took me to the hospital," a policeman wounded in the face and chest told Reuters as doctors tended his wounds. He declined to be named.Tensions risingIn Baghdad, five explosions hit mainly Shi'ite areas in what looked like coordinated attacks, killing nine people and wounding 26, police and hospital sources said,The biggest attack was in the southwestern Amil district, where a car bomb aimed at day laborers killed three and wounded nine, sources said.A car bomb targeting the health minister's motorcade went off in the central Haifa district, killing two civilians and wounding at least four of the minister's guards, a police source said. His spokesman said five guards were wounded in the attack.Car and roadside bombs also went off in Baghdad's Kadhimiya, Palestine Street and Zaafaraniya districts.A political crisis erupted in Iraq in December when the Shi'ite-led government tried to remove Sunni Deputy Prime Minister Saleh al-Mutlaq and sought an arrest warrant for Sunni Vice President Tareq al-Hashemi on charges he ran death squads.Critics of Prime Minister Nuri al-Maliki viewed the moves against two senior Sunni politicians as an attempt by the Shi'ite premier to consolidate power, and many Sunnis fear he is trying to sideline them from government.Maliki has said the charges against Hashemi were brought by the judicial system and his supporters say he is following democratic norms, not abusing them. Elsewhere in northern Iraq, two car bombs targeting government-backed Sunni Sahwa militia went off in Samarra, two blasts hit Baquba, a roadside bomb exploded in Mosul and another roadside device exploded in Taji.In the mainly Sunni Muslim province of Anbar in the west, two car bombs targeting police killed four and wounded 10 in Ramadi while a roadside bomb wounded four people in Falluja.Attacks in Iraq are mostly blamed on Sunni Arab insurgents who have refused to lay down arms after the withdrawal of US forces in December.Heightened tension between Shi'ites, Sunnis and Kurds in the fragile coalition government since US troops withdrew in December has raised fears of a return to sectarian strife of the kind that pushed Iraq to the brink of civil war a few years ago.The country is less violent than at the height of sectarian conflict in 2006-07, but bombings and killings still occur on a daily basis, often aimed at Shi'ite areas and local security forces.Kirkuk, home to Arabs, Kurds, Turkmen and others, is at the heart of a long-running dispute between the central government and the autonomous Kurdish region, which claims the city and the region's rich oil reserves.The rift between Baghdad and the Kurds recently worsened when the Kurdistan Regional Government said it was halting oil exports because the central government was not paying oil firms operating in the north.