(Recasts) By Andrew Gray BAGHDAD, June 15 (Reuters) - U.S. Defense Secretary Robert Gates said on Friday Washington was disappointed with the Iraqi government's efforts to pass laws aimed at reconciling the country's warring factions. Gates flew into Baghdad for an unannounced visit to assess a U.S. troop build-up aimed at buying leaders of Iraq's ethnic and religious groups more time to reach a political accommodation and press the government to move faster in passing the laws. His comments were some of the strongest criticism of the Iraqi government, although he took care to stress that Shi'ite Prime Minister Nuri al-Maliki faced "enormous obstacles" and deserved Washington's continued support. Gates arrived on a day when the U.S. military said it had completed its troop build-up to 160,000 soldiers. Nearly 30,000 extra troops have been sent to Iraq, mainly to secure Baghdad. The effort has been costly for U.S soldiers. May was the third deadliest month for U.S. troops since the start of the U.S.-led invasion in 2003, with 126 killed. The military said on Friday that four more soldiers were killed on Thursday, taking the June toll to 42 and 3,519 in total since 2003. Gates is the third senior U.S. official to visit Baghdad this week, following in the footsteps of the top U.S. military general in the Middle East, Admiral William Fallon, and U.S. Deputy Secretary of State John Negroponte. He said he would echo their message to Maliki and other Iraqi leaders -- speed up passage through parliament of legislation that includes laws on distributing oil revenues, control of regional oil fields and holding provincial elections. "It is the same message that I have been delivering since December, that our troops are buying them time to pursue reconciliation, that frankly we are disappointed with the progress so far," Gates told journalists travelling with him. He said he hoped that Wednesday's attack on the revered Shi'ite al-Askari mosque in the city of Samarra, in which the mosque's minarets were destroyed, would not further delay political progress. REPRISALS The mosque's famed golden dome was blown up in an attack in February 2006, unleashing a wave of sectarian violence that has pushed Iraq to the brink of civil war, killed tens of thousands and displaced some 2 million people. Both attacks were blamed on Sunni Islamist al Qaeda. This time there have been only scattered reprisal attacks, mainly targeting Sunni Arab mosques. In the latest attack, gunmen posing as photographers blew up the largest Sunni mosque in the southern Iraqi province of Basra. Immediately after the Samarra bombing, the Iraqi government imposed a three-day curfew in Baghdad. On Friday night, it said it was extending it until Sunday. While the curfew officially applies to people and vehicles, residents have been allowed to walk to shops to stock up on food and other necessities. Gates said in his talks with Iraqi political leaders he would encourage them to make progress in passing the laws, which Washington sees as crucial to bringing minority Sunni Arabs more firmly into the political process. But he said it remained to be seen whether the parliament would be able to pass the laws, which also include a measure allowing former supporters of Saddam Hussein to hold public office, by September. That is when the top U.S. commander in Iraq, General David Petraeus, and U.S. ambassador Ryan Crocker are due to make an assessment on whether the U.S. troop build-up is succeeding in taming the Sunni Arab insurgency and curbing sectarian violence. With the newly arrived U.S. troops only expected to be fully operational by August, he was asked whether September was too soon to make such an assessment. "There is still a lot of uncertainty but I think we will have some sense of direction and trends on where we are heading," he said. Iraq's political blocs have so far shown a reluctance to compromise on any of the key issues. Analysts say Shi'ites, Sunni Arabs and Kurds in Maliki's coalition government are too divided to reach a political accommodation on their own. In its quarterly report on Iraq published this week, the Pentagon said it was too soon to assess the military crackdown. While violence was down in Baghdad, the overall level was unchanged in Iraq because militants had simply moved their bases outside the capital, it said.
