Iraq has detained 11 security officers for questioning about security failures that led to the bloodiest day in Baghdad in more than a year.
The Iraqi government has raised the death toll from Wednesday's bomb and mortar attacks to at least 100. More than 500 other people were wounded.
An Iraqi army spokesman told the French news agency that regulations instruct security officers to prohibit trucks of the sort that exploded Wednesday from approaching government ministries.
Tightened security Thursday failed to prevent another bombing in the Iraqi capital. Officials say a bomb strapped to a bicycle killed two people and wounded at least 10 in central Baghdad.
The carnage in Baghdad Wednesday prompted Iraqi Prime Minister Nouri al-Maliki to vow an immediate re-evaluation of the government's security methods.
Truck bombs exploded minutes apart outside the foreign ministry and finance ministry. Police say mortar or rocket attacks hit other government buildings and commercial areas in the capital.
In an interview with VOA Kurdish service, Deputy Interior Minister Hussein Ali Kamal blamed the attacks on al-Qaida fighters and remnants of Iraq's Baathist regime of the late Saddam Hussein.
Iraqi security forces say they arrested two al-Qaida members after intercepting a vehicle filled with explosives.
The U.N. Security Council and the United States condemned the bombings. White House spokesman Robert Gibbs said the attacks show how far extremists will go to wreak havoc.
Some information for this report was provided by AFP, AP and Reuters.