Iraq announced the arrests of dozens of military and security personnel over the attacks on government buildings in Baghdad that killed 155 people, the Iraqi capital's military spokesman said Thursday.

Maj. Gen. Qassim al-Moussawi told The Associated Press that 11 army officers and 50 security officials have been taken into custody over Sunday's bombings — the worst attacks in Iraq in over two years.

The massive blasts at the Justice Ministry and the Baghdad Provincial Administration caused outrage among many Iraqis, who question the ability of the government to protect its people ahead of parliamentary January's elections and the withdrawal of U.S. troops from Iraq.

The arrests were the first reported by officials. Al-Moussawi did not say if those detained were suspected of involvement in the blasts or negligence in carrying out their duties in protecting Baghdad.

On Wednesday, Secretary-General Ban Ki-moon said he is sending a senior U.N. official to Baghdad in response to a request from Iraq's prime minister for a U.N. Security Council investigation of two previous bombing of two ministries in August. Those attacks killed more than 100 people.

Ban said that Assistant Secretary-General for Political Affairs Oscar Fernandez-Taranco will go to Baghdad "for preliminary consultations related to Iraq's security and sovereignty" and discussions on how the United Nations can help.

Ban said he decided to send Fernandez-Taranco to Baghdad before Sunday's bombings.

Iraq's Prime Minister Nouri al-Maliki sent a letter to Ban in early September requesting that he ask the Security Council to establish an independent investigation commission into the August bombings.

Iraq has blamed an alliance between Al Qaeda in Iraq and Saddam Hussein's outlawed Baath Party for the pair of truck bombings on Aug. 19 outside the Foreign and Finance ministries in Baghdad that killed about 100 people.

Al Qaeda's umbrella group in Iraq claimed responsibility for the August attack and for Sunday's bombings, raising fears Iraq will return to violence that raged across the country in 2006 and 2007.