The Islamic State of Iraq, which includes al-Qaida in Iraq and other allied Sunni insurgent factions, boasted that its operative easily passed through checkpoints before detonating his explosives belt in a crowd of officers and recruits outside army headquarters Tuesday.
The bomber was able to "break all barriers" and strike "Shiite infidels and other apostates who were selling their religion," the group said in a statement posted on a militant website.
The Iraqi army's recruitment drive aimed to hire soldiers from of the country's poorest Shiite areas. The Islamic State of Iraq is a Sunni extremist group that considers Shiites heretics.
The bombing, which also wounded at least 125 people, once again raised concerns about the Iraqi security forces' readiness to protect their country at a time when all but 50,000 U.S. troops are heading home.
A senior adviser to Iraq's top Shiite cleric blasted the country's police and military leadership Friday for failing to protect military recruits despite repeated attacks on them in the past.
"Several attacks have occurred against gatherings of recruits, yet security forces failed to take precautionary measures to protect them," said Sheik Abdul-Mahdi al-Karbalaie during Friday's sermon in the holy city of Karbala.
Al-Karbalaie is a top representative of the revered cleric Grand Ayatollah Ali al-Sistani, whose views carry great weight with Iraq's Shiite majority. Al-Karbalaie called on the government to take "firm action" against those responsible for the security breach.
Suspected Sunni militants have frequently targeted Iraq's policemen and soldiers looking to expose the inability of the Shiite-dominated government to protect the country, particularly in light of the looming departure of the U.S. military.
The U.S. plans to withdraw all combat forces by Aug. 31, leaving only 50,000 troops to help train Iraqi security forces. As of Friday, an estimated 52,000 U.S. soldiers were still in Iraq.
A bomb hidden in a trash heap killed three people and wounded three more on Friday in Baghdad's mainly Sunni neighborhood of Dora. Gunmen also killed a senior police officer in an ambush as he was driving with his wife and two children in western Baghdad.
The attacks were reported by police and hospital officials who spoke on condition of anonymity because they weren't authorized to release the information.
North of Baghdad, a local leader of a government-backed Sunni group fighting al-Qaida in Iraq was shot dead as he was walking near his home in Baqouba, police spokesman Maj. Ghalib al-Karkhi said.
Also Friday, a deputy police commander in a village near Baqouba escaped an assassination attempt after a bomb exploded near his car, wounding two of his guards, al-Karkhi said.