Yemen’s opposition rejected on Monday a Gulf Arab initiative for President Ali Abdullah Saleh to step down, because it appeared to offer him immunity from prosecution, while Saleh welcomed the plan.

Gulf Arab foreign ministers meeting late Sunday in the Saudi capital, Riyadh, said publicly for the first time that the framework of their mediation effort involved Saleh standing down, though they did not say when that would occur.

The ministers of the Gulf Cooperation Council (GCC) called for a meeting of parties to the Yemeni conflict in Saudi Arabia but set no date.

“Who would be a fool to offer guarantees to a regime that kills peaceful protesters? Our principal demand is that Saleh leaves first,” opposition spokesman Mohammed al-Sabry said.

Diplomatic sources say Saleh has dragged his heels for weeks over U.S. attempts to get him to agree to step down and end protests that have crippled the country since February, maneuvering to win guarantees that he and his sons would not face prosecution.

With more than 100 protesters killed in clashes with security forces, activists have said they want to see legal action against Saleh and his sons, who occupy key security and political posts.

Tens of thousands filled the streets of Sanaa, Taiz, Hudaydah, Ibb and the southeastern province of Hadramaut on Monday to protest the GCC plan, witnesses said.

Maj. Gen. Ali Mohsen al-Ahmar, a distant kinsman of Saleh’s whose units are protecting protesters in Sanaa, the capital, said Monday he welcomed the details of the GCC plan announced in Riyadh.

“He hopes all parties will accept this initiative and not miss this opportunity,” a statement from his office said.

Shortly after the opposition rejected the initiative, Saleh’s office issued a statement saying he accepted it.

“The presidency welcomes the efforts of our brothers in the Gulf Cooperation Council to solve the current crisis in Yemen,” the statement said from his office said.

Saleh “has no reservations about transferring power peacefully within the framework of the constitution,” it added, in language Saleh has used before to argue that he should oversee a transition involving new elections.