BEIRUT — Syrian opposition groups on Sunday rejected a UN-brokered peace plan for a political transition in Syria, calling it ambiguous and a waste of time and vowing not to negotiate with President Bashar al-Assad or members of his "murderous" regime. An international conference in Geneva on Saturday accepted UN special envoy Kofi Annan's plan that calls for the creation of a transitional government, but at Russia's insistence the compromise agreement left the door open to Syria's president being part of the interim administration. The US backed away from insisting that the plan should explicitly call for Assad to have no role in a new Syrian government, hoping the concession would encourage Russia to put greater pressure on its longtime ally to end the violent crackdown that the opposition says has claimed more than 14,000 lives. Syrian opposition figures rejected any notion of sharing in a transition with Assad. "Every day I ask myself, do they not see how the Syrian people are being slaughtered?" veteran Syrian opposition figure Haitham Maleh asked. "It is a catastrophe, the country has been destroyed, and they want us then to sit with the killer?" Maleh described the agreement reached in Geneva as a waste of time and of "no value on the ground." "They Syrian people are the ones who will decide the battle on the ground, not those sitting in Geneva or New York or anywhere else," he said by telephone from Cairo, where opposition groups are to meet Monday. Bassma Kodmani, a Paris-based spokesperson for Syria's main opposition group, the Syrian National Council, said the agreement is "ambiguous" and lacks a mechanism or timetable for implementation. "We cannot say that there is any positive outcome today," she said. "The Syrians will not accept engaging in any political track while the killing continues." There was no reaction from the Syrian regime to the Annan plan, but Assad has repeatedly said his government has a responsibility to eliminate terrorists and will not accept any non-Syrian model of governance. State-run newspaper Al-Thawra said Sunday "the Syrians are the ones who can determine their future." The UN plan calls for establishing a transitional government of national unity, with full executive powers, that could include members of Assad's government and the opposition and other groups. It would oversee the drafting of a new constitution and elections. US Secretary of State Hillary Clinton insisted on Saturday that Assad would still have to go, saying it is now "incumbent on Russia and China to show Assad the writing on the wall" and help force his departure." "There is a credible alternative to the Assad regime," she said. "What we have done here is to strip away the fiction that he and those with blood on their hands can stay in power." Annan was appointed the special envoy in February, and in March he submitted a six-point peace plan that he said the Assad regime accepted. It led to the 12 April ceasefire that failed to hold. UN observers sent to monitor the ceasefire suspended their patrols in Syria on 16 June due to a spike in violence and have been confined to their hotels since. Moscow had refused to back a provision that would call for Assad to step aside, insisting that outsiders cannot order a political solution for Syria and accusing the West of ignoring the darker side of the Syrian opposition. The opposition has made clear it would not take part in a government in which Assad still held power. Russian Foreign Minister Sergey Lavrov underlined that the plan does not require Assad's ouster, saying there is "no attempt in the document to impose on the Syrian people any type of transitional process."