Rupert Colville, a spokesman for the U.N. High Commissioner for Human Rights, said Tuesday "international law is pretty clear" that amnesty cannot be granted to someone who could face war-crimes charges.

Saleh has balked at a U.S.-backed plan by Saudi Arabia and five of its allies in the Gulf Cooperation Council to hand power to his deputy and resign in exchange for immunity.

Many Yemenis accuse Saleh, Yemen's leader of 33 years, of fueling civil war by clinging to power despite eight months of massive street protests — some fired on by forces loyal to Saleh.