The list includes International Islamic Council, International Union of Muslim Scholars, led by prominent Egyptian scholar Sheikh Yusuf Al Qaradawi, and 11 individuals.
The four Arab countries boycotting Qatar added 11 more individuals and two other entities to their "terrorist" blacklists for the Gulf state, Saudi state news agency SPA reported on Thursday.
The additions include two Doha-based NGOs: the International Islamic Council and the International Union of Muslim Scholars (IUMS) led by prominent Egyptian scholar Sheikh Yusuf Al Qaradawi.
"The two entities listed are two terrorist organisations that promote terrorism by using Islamic rhetoric as a cover to facilitate terrorist activities," said the statement issued by Saudi Arabia, Egypt, the United Arab Emirates (UAE) and Bahrain.
The move deepened the rift between the four countries and Qatar, the world's top gas exporter and host to the biggest US military base in the Middle East.
The countries cut ties with Qatar in June, accusing it of financing militants in Syria and allying with Iran.
Qatar, for its part, has denied the accusations, describing the attempts to isolate it as a breach of international law.
Muslim Brotherhood targeted
The Saudi-led quartet also added 11 individuals to their lists, including the acting Muslim Brotherhood leader Mahmoud Ezzat Ibrahim.
The Brotherhood movement led the Arab Spring protests in 2011 that toppled some autocrats in the Middle East and North Africa.
The Gulf States' rulers see the group, whose political ideology challenges the principle of dynastic rule, as a security threat.
The IUMS membership includes the Saudi cleric Salman Al-Awdah, who was arrested by Saudi authorities in September, the Tunisian Rached Ghannouchi, head of the Ennahda party, and Moroccan scholar Ahmed Raissouni.
The IUMS has yet to comment on the development.
Mediation efforts of the Qatar crisis led by Kuwait, Turkey and shuttle diplomacy by Western officials, including the US Secretary of State Rex Tillerson, have failed to end what has become the worst rift between Gulf Arab states in years.