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Against this backdrop of a worsening humanitarian crisis, U.N.-Arab League Syria envoy Lakhdar Brahimi will meet senior diplomats in Geneva on Tuesday in a new bid to prepare a long-delayed peace conference.
Russia, a close ally of Syrian President Bashar al-Assad, and China have vetoed three Security Council resolutions since October 2011 that would have condemned the government and threatened it with sanctions.
The talks in the Swiss city aim to pave the way for a new international conference focused on ending the 31-month conflict in Syria, which has left more than 120,000 people dead and forced millions to flee their homes.
Hoping to build on the momentum of a U.S.-Russia accord reached in September to destroy Syria's chemical arsenal by mid-2014, Brahimi has been traversing the region to rally support for the conference, dubbed Geneva II.
But late on Monday Syria's information minister declared that the regime would not take part in the proposed conference if the aim is for Assad to give up power.
"President Bashar al-Assad will remain head of state," Omran al-Zohbi said in comments carried by the official SANA news agency.
The comments came after Secretary of State John Kerry met his Saudi counterpart, Foreign Minister Prince Saud al-Faisal in Riyadh on Monday to smooth over differences on Syria.
While Kerry reiterated that the U.S. opposes military intervention to end the bloodshed in Syria, Saud said negotiations "shouldn't just go on indefinitely," in reference to the proposed peace conference.
Arab League foreign ministers met in Cairo on Sunday to push the Syrian opposition to attend Geneva II.
At the start of the meeting in the Egyptian capital, Ahmed Jarba, who heads the main umbrella opposition National Coalition, emphasized the group's commitment to attending Geneva II only as a united front and reiterated its unequivocal demand for a ceasefire during the talks.
The coalition has said it plans to meet in Istanbul on Saturday to decide whether to attend the Geneva peace talks, but the Syrian National Council, a key member of the bloc, has threatened to quit if it does so.
Al Jazeera and wire services