World powers and neighbors of Syria have agreed on a road map for political transition to end 16 months of bloodshed but left open the question of whether President Bashar al-Assad can take part.
However, after talks in Geneva, international envoy Kofi Annan said he doubted Syrians would pick individuals with "blood on their hands."
"I think people with blood on their hands hopefully are not the only people in Syria," Annan said. "I think the government will have to be formed through discussion, negotiations, and by mutual consent. And I will doubt that the Syrians -- who have fought so hard for their independence, to be able to have a say how they are governed and who governs them -- will select people with blood on their hands to lead them."
Under the UN plan, the transitional government would oversee the drafting of a new constitution and elections.
Annan warned failure to resolve the crisis in Syria could ignite the region and turn into an international crisis.
"We are determined to work together urgently and intensively to bring about an end to the violence and human rights abuses and the launch of a Syrian-led political process leading to a transition that meets the legitimate aspirations of the Syrian people and enables them independently and democratically to determine their own future," Annan told reporters.
Meanwhile, U.S. Secretary of State Hillary Clinton said Assad's "days are numbered."
"In deciding to accept minor textual changes, we and our partners made absolutely clear to Russia and China that it is now incumbent upon them to show Assad the writing on the wall," Clinton said. "I do not believe that anyone in the Assad regime ever thought we could come out with a unified statement today expressing not only the concerns but a path forward that would include Russia and China, and he needs to hear loudly and clearly that his days are numbered."
Russian Foreign Minister Sergei Lavrov, however, said it was up to the Syrians, not the United Nations, to decide who will govern the country.
"In the original version, there was a phrase to the effect that people should be excluded who are standing in the way of peace or preventing peace," Lavrov said. "That is not consistent with the principal inclusiveness of the political process in Syria. it is not consistent with the provisions of the UN charter on noninterference in internal affairs of sovereign states, and it is not consistent with the logic of the document adopted today, which says that the fate of the country should be decided by Syrians themselves."
Chinese Foreign Minister Yang Jiechi called for all sides to end the violence "without attaching any conditions."
Rami Abdul-Rahman, director of the Britain-based Syrian Observatory for Human Rights, said the Syrian opposition would not take part in any transitional government "while Assad is still in power."
British Foreign Secretary William Hague noted that UN Secretary-General Ban Ki-moon told diplomats that a UN monitoring mission in Syria would have to be pulled back if no diplomatic solution was found.
Meanwhile, inside Syria, the violence continues.
Opposition activists said Syrian forces killed more than 30 people on June 30 in Damascus when they fired a mortar bomb into a funeral procession for a man who had died in shelling the day before.
The United Nations says violence in the country has worsened since a cease-fire deal in April.
With reporting by AP, AFP, and Reuters