BAGHDAD - Al Qaeda claimed responsibility on Tuesday for simultaneous raids on two Iraqi prisons and said more than 500 inmates had been set free in the operation, one of its most brazen in Iraq.
The Islamic State of Iraq and the Levant, formed earlier this year through a merger of al Qaeda's affiliates in Syria and Iraq, said it had stormed the high-security jails after months of preparation.
Monday's attacks came exactly a year after the leader of al Qaeda's Iraqi branch, Abu Bakr al-Baghdadi, launched a "Breaking the Walls" campaign that made freeing its imprisoned members a top priority, the group said in a statement.
Sunni Islamist militants have in recent months been regaining momentum in their insurgency against Iraq's Shi'ite-led government, which came to power after the US invasion to oust Saddam Hussein.
The group said it had deployed suicide attackers, rockets, and 12 car bombs, killing 120 Iraqi guards and SWAT forces in the attacks in Taji and Abu Ghraib, the prison made notorious a decade ago by photographs showing abuse of prisoners by US soldiers.
"In response to the call of the mujahid (holy warrior) Sheikh Abu Bakr al-Baghdadi to seal the blessed plan of "Breaking the Walls"... the mujahideen brigades set off after months of preparation and planning to target two of the biggest prisons of the Safavid government," read the statement posted on militant forums.
Safavid is a reference to the dynasty that ruled Iran from the 16th to 18th centuries and is used by hardline Sunnis as a derogatory term for Shi'ite Muslims.
Sectarian tensions across the region have been inflamed by the civil war in Syria, which has drawn in Shi'ite and Sunni fighters from Iraq and beyond to fight against each other.
The violence has raised fears of a return to full-blown conflict in Iraq, where ethnic Kurds, Shi'ites and Sunnis have yet to find a stable way of sharing power.
Meanwhile insurgents have been regrouping and gaining recruits from the country's Sunni minority, which resents Shi'ite domination since Saddam's overthrow.
Some politicians said the prison assaults showed the government was losing its grip on security. So far in July, almost 700 people have been killed in militant attacks, according to violence monitoring group Iraq Body Count.
That is still well below the height of Sunni-Shi'ite bloodletting that followed the US invasion, when the monthly death toll sometimes topped 3,000.