Syrian opposition groups have rejected a United Nations-backed plan for a political transition in Syria, calling it “ambiguous” and “a farce” while ruling out any possibility of sharing power with President Bashar al-Assad.

A Paris-based Syrian National Council spokeswoman, Bassma Kodmani, said Sunday that Syrians “will not accept engaging in any political track while the killing continues.”

Dozens of civilians were reportedly killed the day before, including at least 30 when a powerful explosion hit a funeral procession in a suburb of the capital, Damascus. Activists blamed government forces for the blast.

An international conference in Geneva on Saturday accepted a watered down version of U.N. envoy Kofi Annan's plan for the creation of a transitional government in Syria. But at Russia's insistence the compromise agreement left the door open to Mr. Assad being part of the interim administration.

Burhan Ghalioun, a senior SNC member and the group's former head, told pan-Arab Al-Arabiya television that “this is the worst international statement yet to emerge from talks on Syria.” According to the SNC's official Facebook page, he described as a “mockery” the notion that Syrians should negotiate with “their executioner, who has not stopped killing, torturing… and raping women for 16 months.”

The Geneva deal was forged amid deep divisions between Western and Arab countries and China and Russia on how to end the violence. U.S. Secretary of State Hillary Clinton insisted Mr. Assad cannot be a part of Syria's future. She said it is now “incumbent on Russia and China to show Assad the writing on the wall.''

Moscow and Beijing had refused to back a provision that would call for Mr. Assad to step aside, with Russia insisting that outsiders cannot order a political solution for Syria.

Russian Foreign Minister Sergei Lavrov said the plan does not require the Syrian president leave power, saying there is “no attempt in the document to impose on the Syrian people any type of transitional process.''

The wording of a final communique from the meeting calls for “clear and irreversible” steps toward a political transition. It says a transitional body must be formed through “mutual consent,” and could include current members of government.

Earlier in the meeting Mr. Annan warned the participants – the United States, Russia, China, Britain, France and envoys from Arab countries – that if they failed to act, they could face an international crisis of “grave severity.''