Saudi Arabia declared the Muslim Brotherhood a terrorist group along with three other militant groups operating througout the region, Al Arabiya reported on Friday.
Other groups included on the terror lists are al-Nusra Front, the Islamic State of Iraq and Sryia (ISIS), and Riyadh's branch of Hezbollah.
Saudi ctizens numbering in the hundreds have joined ISIS and Nusra to fight in the Syria conflict.
Riyadh has announced a 15 day ultimatum for fighters to return home. Fighters who shun the decree and later return face stiff penalties, including up to 20 years in jail for fighting abroad.
