A car bomb targeting an Iraqi police patrol exploded in central Baghdad on Wednesday (October 18, 2006), wounding four civilians, police said. They said that the car was parked in Al-Nidhal Street and went off as police patrol drove past. Earlier, two civilians were wounded in a bomb blast targeting a U.S. military convoy in the southeast of the capital, police said. The blast took place in Maysaloon Square. "The Americans drove from here and a lorry was parking here and the car came and parked next to it and minutes later a bomb went off," said eyewitness Ali al-Moussawi who lives in an apartment overlooking the street. "Three patrols were there at night, one is here and the second one there and the third one there, so when did the bomber come and plant it? I just want to know when did he plant it. This is all what I want to know," al-Moussawi added. No casualties were reported among the U.S. troops. The violence continued as Prime Minister Nuri al-Maliki travelled to the holy city of Najaf and met Grand Ayatollah Ali al-Sistani, the leading Shi'ite cleric in Iraq and firebrand cleric Moqtada al-Sadr. Maliki said his visit to Iraq's top Shi'ite cleric Sistani was meant to gather momentum for his reconciliation move to help stop the bloodshed of the Iraqi people and stamp out sectarian killings. "We are moving on all the levels, which have a leverage on the political and social status in order to find a powerful atmosphere to convey the real message that the Iraqi people and the Iraqi government want and which represents Iraq's interests," Maliki told reporters after meeting with Sistani. Maliki, a Shi'ite, who took office almost five months ago, is under pressure to the ease violence which has plagued Iraq. U.S. officials are growing increasingly impatient over Maliki's inaction to crack down on militias, blamed for many of the sectarian killings gripping Iraq, including a weekend rampage north of Baghdad that left more than 60 killed. Maliki also met with firebrand Shi'ite cleric Moqtada al-Sadr, whose militia of Mehdi army have engaged in clashes with the U.S. and Iraqi forces in the southern city of Diwaniya earlier this month. Speaking at a joint news conference, Sadr said the Iraqi people have the right to decide on federalism. "It is up to the Iraqi people to decide on federalism or any other issue and If the the people wants federalism, it is Ok and if it is not, it is their legitimate right," said Sadr. Although the principle of federalism is enshrined in the constitution, the law passed by parliament on the 11th of October is the first to set up a system that will allow provinces to merge into autonomous regions in 2008. But opponents of the bill -- including not only Sunni Arabs but secular parties and the bloc of anti-American cleric Sadr -- expressed fears that the federalism plan could increase sectarian tensions and push the country further toward civil war. Asked about a proposed meeting on October 19-20 in Saudi Arabia in Mecca to bring together Iraqi Sunni and Shi'ite scholars and urge them to seek an end to the violence to allow the two sides to be reconciled, Sadr said he hoped the meeting would be held in Baghdad. "I support all the conferences that serve the benefits of the Iraqi people, though I think it was better if it was held in Iraq and Iraq was the one which plays a host to such conferences, but God willing, Muslims' efforts, Arabs' efforts and the efforts of our brothers and neighbours will help serve the interest of the Iraqi people." The U.S. military on Tuesday (October 17) arrested an aide to Sadr, a pro-government Shi'ite cleric who heads the Mehdi Army militia. The man, identified by Sadr's office as Sheikh Mazin al-Saedi, was freed on Wednesday after Maliki ordered his release. Maliki, a member of the ruling Shi'ite alliance which is accused by some of fostering sectarian death squads, appeared to acknowledge the problem. He has pledged several times to rein in militias, but disbanding them could put him in a precarious situation because they are tied to political parties in his coalition. On Sunday (October 15), Maliki renewed a pledge to disband militias.