Saudi Arabia has listed the Muslim Brotherhood and two Syrian jihadist groups as terrorist organisations and ordered citizens fighting abroad to return within 15 days or face imprisonment.
Friday's move represents a major escalation against the Muslim Brotherhood of deposed Egyptian president Mohamed Morsi and indicates rising concern in Riyadh over the possible return of battle-hardened Saudis extremists from Syria.
In addition to the Muslim Brotherhood, Saudi listed Al-Nusra Front, which is al-Qaeda's official Syrian affiliate, and the Islamic State of Iraq and the Levant (ISIL), a rogue group fighting in both Syria and Iraq, as terrorist organisations.
It also listed as terrorist groups the Shiite Huthi rebels fighting in northern Yemen and a little-known internal Shiite group called Hezbollah in the Hijaz.
Saudi and other conservative Gulf monarchies have long been hostile towards the Muslim Brotherhood, fearing that its brand of grass-roots activism and political Islam could undermine their authority.
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Riyadh is a staunch supporter of the Sunni-led rebels battling to overthrow Syrian President Bashar al-Assad but has long feared blowback from radical jihadist groups.
King Abdullah last month decreed jail terms of up to 20 years for belonging to "terrorist groups" and fighting abroad.
Similar sentences will be passed on those belonging to "extremist religious and ideological groups, or those classified as terrorist organisations, domestically, regionally and internationally", state news agency SPA said at the time.
Supporting such groups, adopting their ideology or promoting them "through speech or writing" would also incur prison terms, the decree added.
