A Saudi Interior Ministry statement said King Abdullah approved the findings of a committee entrusted with identifying extremist groups referred to in a royal decree earlier last month. The decree punishes those who fight in conflicts outside the kingdom or join extremist groups or support them.
The king's decree followed the kingdom enacting a sweeping new counterterrorism law that targets virtually any criticism of the government.
The Muslim Brotherhood has been targeted by many Gulf nations since the July 3 military overthrow of Islamist President Mohammed Morsi in Egypt, himself a Brotherhood member. Saudi Arabia has banned Brotherhood books from the ongoing Riyadh book fair and withdrew its ambassador from Qatar, a Brotherhood supporter, along with Bahrain and the United Arab Emirates.
In a statement, the Muslim Brotherhood condemned Saudi Arabia's decision.
"It is one of the founding principles of the group not to interfere in matters of other states, and this new position from the kingdom is a complete departure from the past relationship with the group, since the reign of the founding king until now," the statement read.
Egyptian Foreign Ministry spokesman Badr Abdel-Attie praised the decision, saying it "reflects the coordination and solidarity" between Egypt and Saudi Arabia. He said he hopes that other countries make the same decision.
"We expect other countries to fulfill their responsibilities in the fight against terrorism," Abdel-Attie told journalists Friday.
The Saudi statement, carried by the official Saudi Press Agency, identified the other terrorist groups named as al-Qaida's branches in Yemen and Iraq, the Syrian al-Nusra Front, Saudi Hezbollah and Yemen's Shiite Hawthis. It said the law would apply to all the groups and organizations identified by the United Nations Security Council or international bodies as terrorists or violent groups. It said the law also would be applied to any Saudi citizen or a foreigner residing in the kingdom for propagating atheism or pledging allegiance to anyone other than the kingdom's leaders.
The counterterrorism law bans meetings of the groups inside or outside of the kingdom and covers comments made online or to media outlets.
The unprecedented and harsh prison terms seem aimed at stemming the flow of Saudi fighters going to Syria, Yemen or Iraq. The Syrian civil war is believed to have drawn hundreds of young Saudis, worrying some in the kingdom that fighters could return radicalized and turn their weapons on the monarchy.
Influential Saudi clerics who follow the kingdom's ultraconservative religious Wahhabi doctrine encouraged youths to fight in the war and view it as a struggle between Syria's Sunni majority and President Bashar Assad's Alawite, Shiite-backed minority.
Saudi officials and some clerics have spoken out against young Saudis joining the war. However, the Saudi government backs some rebel opposition groups in Syria with weapons and aid.
The new law is also believed to reflect pressure from the U.S., which wants to see Assad's overthrow but is alarmed by the rising influence of hard-line foreign jihadists — many of them linked to al-Qaida — among the rebels. U.S. President Barack Obama is scheduled to fly to Saudi Arabia and meet King Abdullah this month.
Meanwhile in Qatar, outspoken Egyptian cleric Youssef el-Qaradawi did not deliver his usual sermon on Friday. The reasons for his absence were not made immediately public. His past sermons, in which he publicly criticized the UAE and other Gulf countries for their support of Egypt's new government in its crackdown on the Brotherhood, led to outrage among Qatar's neighbors who saw the comments as an attack on their sovereignty.
Associated Press writers Maamoun Youssef in Cairo and Abdullah Ribhi in Doha, Qatar, contributed to this report.