BEIRUT - Syria's main rebel commander urged Kofi Annan on Thursday to announce that his peace plan has failed and free insurgents from any commitment to a truce deal, which the United States said may collapse and trigger a wider Middle East crisis.
Colonel Riad al-Asaad, who is based in Turkey, contradicted a statement by the rebels inside Syria who issued a 48-hour ultimatum on Wednesday for President Bashar al-Assad to abide by the conditions of Annan's plan.
"There is no deadline, but we want Kofi Annan to issue a declaration announcing the failure of this plan so that we would be free to carry out any military operation against the regime," Asaad told Al Jazeera television.
Annan's plan has not stemmed bloodshed in Syria and the U.S. envoy to the United Nations warned that unless the Security Council acts swiftly to pressure Syria to end its crackdown on opposition, countries may act outside of the world body.
Susan Rice outlined what she said was both a worst case and most likely scenario in which "the violence escalates, the conflict spreads and intensifies ... It involves countries in the region, it takes on increasingly sectarian forms, and we have a major crisis not only in Syria but in the region."
In that case Syria - a mainly Sunni Muslim country whose Alawite leader is allied to Shi'ite Iran - would become "a proxy conflict with arms coming in from all sides" and world powers would consider taking unilateral actions, Rice said.
The rival statements from rebels inside and outside Syria showed once again how deep divisions run between Assad's foes, who have failed to unify either political or military operations more than 14 months after Syria's uprising first broke out.
U.N. observers on Wednesday reported the discovery of 13 bodies bound and shot in eastern Syria, adding to the world outcry over the massacre last week of 108 men, women and children in the western town of Houla. The United Nations has said the army and pro-Assad gunmen were probably responsible for the Houla killings, an accusation that Damascus has denied.
U.N. Secretary-General Ban Ki-moon warned on Thursday that another atrocity could pitch Syria into a devastating civil war "from which the country would never recover".
A senior army commander in Israel, which seized the Golan Heights from Syria in a war 45 years ago, said the country was heading for collapse and would become a "warehouse of weapons" for Islamist militants.
Asaad said rebels had so far honoured their commitments to Annan's plan. But activists have reported frequent attacks by militants and army defectors on Assad's forces since the April 12 ceasefire agreement.
Government forces have also bombarded towns, fired on protesters and attacked rebel strongholds, killing many hundreds of people in the last seven weeks, the activists say.