SANA, Yemen — Leaders of the Houthi rebels announced on Saturday that they had appointed four key ministers from the recently ousted government to a national security committee, part of their efforts to begin building institutions to replace those disbanded by their effective coup.

The appointments appeared to be aimed at reassuring Western countries and regional powers like Saudi Arabia that the militants could be inclusive and trustworthy, particularly in the fight against Al Qaeda in the Arabian Peninsula. But it remained unclear if the men had accepted the posts and if their announced participation was voluntary.

But if the move was meant to allay the fears of the Saudis, who have traditionally been major aid donors to Yemen, it did not seem to work.

Saudi Arabia and its allies in the six-member Gulf Cooperation Council denounced the Houthis’ new governing plan on Saturday as a “coup” and called for the United Nations Security Council to bring it to an end, according to a statement carried by the official Saudi Press Agency.