Saudi Arabia's Council of Senior Scholars declared that the Muslim Brotherhood was a terrorist group that did not represent Islam, the Saudi Press Agency reported.
The Brotherhood is officially designated a terrorist group in Arab countries including the UAE, Saudi Arabia, Bahrain and Egypt.
Yusuf Al Qaradawi, the spiritual leader of the Brotherhood, which was formed in Egypt in 1928, has been banned from Britain, France and the US for his extremist views, which include condoning suicide bombings.
Al Qaradawi, who now lives in Qatar, has also been sentenced to life in prison in his native Egypt.
The council, the kingdom's highest religious body, said the Brotherhood was "a deviant group" that undermined co-existence in a single nation and stirred rebellion, sedition, violence and terrorism.
"The Muslim Brotherhood group is a terrorist group and it does not represent the method of Islam," the council said.
"Rather, it follows its partisan objectives that are running contrary to the guidance of our graceful religion, while taking religion as a mask to disguise its purposes to practise the opposite, such as sedition, wreaking havoc, committing violence and terrorism.
"The council calls on the public to be careful against this group and stay away from joining it or showing sympathy to it."
The council also said that the Brotherhood spawned other extremist and terrorist groups that have "wreaked havoc" in several countries.
On Monday, dawn raids on groups suspected of operating on behalf of the Muslim Brotherhood and Hamas were carried out by Austrian police in a major crackdown.
Austria's Interior Minister, Karl Nehammer, and the country's lead counter-extremism minister, Susanne Raab, stressed there was a focus on the ideological threats posed by organisations in the country.