Two suicide bombers disguised as senior police officers killed 29 people Monday after infiltrating one of Baghdad's most heavily fortified areas, but died before getting near the US ambassador, senior Iraqi officials and hundreds of others attending National Police day celebrations. The escalating violence following the Dec. 15 elections - at least 498 Iraqis have been killed, including 355 civilians and 143 security forces - came as Iraq's electoral commission again postponed releasing information on last month's contested elections. An Internet site known for publishing extremist material from al-Qaida in Iraq leader Abu Musab al-Zarqawi carried a claim of responsibility for the attack, saying it was in revenge for the alleged torture of Sunni Arab prisoners at an Interior Ministry jails. "The lions of al-Qaida in Iraq were able to conduct a new raid on the Interior Ministry, taking revenge for Allah's religion and the Sunnis, who are being tortured in the ministry's cellars," the statement said. It was posted on an Internet site commonly used by militant groups and could not be independently verified. The claim referred to reports that more than 100 abused prisoners were recently found in two detention facilities run by the Shiite-led Interior Ministry - bolstering complaints by Sunni Arabs about abuse and torture by Interior Ministry security forces. Another statement purportedly by al-Zarqawi rebuked Sunni Arabs for taking part in last month's parliamentary elections, saying they had "thrown a rope" to save US policy. Ibrahim Bahr al-Uloum, who resigned as oil minister last week over increases in consumer fuel prices, again resumed his old post after the prime minister and president asked him to come back, Iraq's Council of Ministers said. Meanwhile, the US military said eight US troops and four American civilians died aboard a US Army Black Hawk helicopter that crashed late Saturday in northern Iraq. The military initially said only that there were eight passengers and four crew aboard. The military statement came after a particularly deadly four-day period for Americans, with 28 killed since Thursday, including 24 troops. With the latest military deaths, at least 2,207 US service members have died since the war started in 2003, according to an Associated Press count. Sunni Arabs expressed anger over a raid by US troops on the headquarters of the Association of Muslim Scholars, a major Sunni clerical group. They said they would hold a special ceremony Tuesday at the Umm al-Qura mosque, which was raided before dawn Sunday. The ceremony was organized by the main Sunni Arab Iraqi Accordance front and the Iraqi Islamic Party and would also mark the start of the four-day Islamic feast of Eid al-Adha. The military said the raid came after a tip from an Iraqi citizen that there was "significant terrorist related activity in the building," and six people were detained. The Association is thought by some to be close to some insurgent groups. "The violations of the occupation forces are continuing and they are endless. The raid on the Um al-Qura mosque is the most recent example," said Muthana Harith al-Dhari, a spokesman for the Association. Police Maj. Falah al-Mohammadawi said two suicide bombers carried out the attacks inside the Interior Ministry compound, a sprawling compound more than one kilometer wide, where National Police Day celebrations were held. The first bomber was shot by the police, although his explosives detonated. A second bomber also detonated his explosives. One bomber was wearing the uniform of an Iraqi police major and the other was dressed as a lieutenant colonel, while both had passes that enabled them to get through checkpoints and into the compound. At least 29 people were killed and 18 injured, mostly policemen, said Ala'a Abid Ali, an official at al-Kindi hospital. The bombs exploded about 500 meters from the celebration attended by US Ambassador Zalmay Khalilzad, Interior Minister Bayan Jabr, Defense Minister Sadoun al-Dulaimi and hundreds of others. The attacks didn't have any effect on the parade and none of the officials were hurt, said Lt. Col. Barry Johnson, a US military spokesman. He said the explosions "had no impact on the ceremony and did not require anybody to take cover." Election results will be released after Eid al-Adha, said Hussein Hindawi, a member of Iraq's electoral commission. It was the second time they had postponed releasing information on the contested election - which Sunni Arab groups said were tainted by fraud. Officials on Monday canceled a news conference where they had hoped to give out more preliminary results, saying they were still auditing returns from about 50 ballot boxes and wanted to announce everything at once. The leader of Iraq's main Sunni Arab political group said after meeting President Jalal Talabani on Sunday that significant headway had been made in forming a government of national unity. Talabani has said that Iraq's political groups could form a coalition government within weeks.