BAGHDAD (Reuters) - A series of explosions, two of them targeting Iranian pilgrims, killed a total of 13 people in Iraq on Saturday and wounded more than 80, sources said. At least six Iranian citizens were killed and 33 were wounded in the incidents, sources said. An official in Tehran denied that any Iranian pilgrims were killed on Saturday. A car bomb in a southwest Baghdad market in the mainly Shia district of Bayaa took the heaviest toll, killing six people and wounding 41 others, an interior ministry source said. In northern areas of the city, two car bombs hit Iranian pilgrims visiting Baghdad for tours of Shia religious sites. The bombings came two days after Iraqi officials said they had arrested 39 Qaeda militants, including top figures in Anbar province, a former al Qaeda stronghold. Al Qaeda is behind the bombings, said Baghdad security spokesman Major General Qassim al-Moussawi. The targeting of Shia areas is an attempt to...inflame sectarian conflict. Militants blew up a car bomb in front of a house used by Iranians as a rest stop in the Kadhamiya district of Baghdad, as well as explosives planted in an adjacent house, killing five people and wounding 18, the interior ministry source said. The explosion completely destroyed the two houses and damaged the rest of the houses in the area, said a man whose home was damaged. We ask the government to focus on checkpoints to prevent the entry of explosives into residential areas. In Baghdads northern Shula district, a car bomb exploded near a bus carrying Iranians, killing two people and wounding 28, sources said. Northern Baghdad hosts the shrine for Imam Moussa al-Kadhim, a mediaeval Shia holy man. During a pilgrimage in 2005, rumours of a bombing on the Bridge of the Imams near the shrine touched off a stampede that killed 1,000 people. An Iranian official said some Iranian citizens were wounded in the attacks. No Iranian pilgrim was killed in Saturdays attacks in Baghdad, said Mehdi Shahsavari, director general of Irans Hajj and Pilgrimage Organisation for International Affairs, Irans student news agency ISNA reported. Nineteen people died and dozens were hurt on Friday when two buses carrying mostly Iranian pilgrims collided on a highway south of Baghdad, a health official said. Overall violence in Iraq has dropped significantly since the peak of sectarian violence in 2006-07, when tens of thousands were killed, but bombings and other attacks still occur daily. Lieutenant General Hussein Kamal, a deputy interior minister, said the latest could have been a reaction to the governments recent successes. Authorities said on Thursday they had scored a major coup with the arrests of the Anbar cell and paraded the suspects before news cameras. This is a kind of pressure exercised by the armed militias and al Qaeda to show that the government and security forces are disabled, despite our achievements, Kamal said.