RIYADH (REUTERS) - The Islamic State in Iraq and Syria (ISIS) group pledged to destroy Saudi Arabian prisons holding its militants after Riyadh's execution of 47 people including 43 convicted Al-Qaeda militants on Saturday (Jan 2).

An article in an online magazine posted on Tuesday (Jan 5) singled out the Al-Ha'ir and Tarfiya prisons where many Al-Qaeda and ISIS militants have been detained. In July, an ISIS supporter killed himself in a car bomb at a checkpoint outside Ha'ir prison near Riyadh.