An Al-Qaeda front group on Tuesday claimed a brazen assault on major prisons in Iraq that freed hundreds of prisoners including senior militant leaders, in a statement posted on jihadist forum Honein.

"The mujahideen (holy warriors), after months of preparation and planning, targeted two of the largest prisons of the Safavid government," said the statement signed by the Islamic State of Iraq and Levant (ISIS), using a pejorative term for Shias.