An al-Qaida-affiliated group in Iraq has claimed responsibility for a carefully planned assault on the Justice Ministry in downtown Baghdad last week. The attack, involving car bombs and gunmen disguised as police, killed at least 24 people.

In a statement posted online on Sunday, the Islamic State of Iraq said the "blessed raid" was "vengeance for the Sunni women" held in the prisons of the Shiite-led government. It described the ministry building as a "tool to fight, terrorize, jail, torture and kill Sunnis."

The Thursday attack in downtown Baghdad came less than a week before the 10th anniversary of the U.S.-led invasion of Iraq, showing how vulnerable this country remains to insurgent attacks.