U.S. Secretary of State John Kerry says he expects Syria's government and the main opposition coalition to attend a peace conference in early June, with the goal of ending their two-year conflict.
Speaking during a visit to Stockholm, Kerry said Tuesday that Russia has informed him that the Syrian government has presented names of potential negotiators. Moscow is a longtime ally of Syrian President Bashar al-Assad.
The top U.S. diplomat said opposition members of the Western-backed Syrian National Coalition also plan to participate in the conference.
Russia and the United States agreed last week to try to arrange the peace talks despite their sharp disagreements about whether Mr. Assad should have a role in Syria's future. Washington has long insisted that Mr. Assad should step down for leading a deadly crackdown on dissent.
Kerry said intensive diplomacy is under way to try to stage the conference, whose location has not been confirmed. Jordanian officials said Western and Arab nations opposing Mr. Assad will hold a "Friends of Syria" meeting in Amman next week to discuss the process.
The top U.S. diplomat also warned Mr. Assad not to boycott the talks, saying that would be a "miscalculation" that would lead to the opposition receiving "additional support" from its allies.
Earlier Tuesday, Syrian state media quoted Information Minister Omran al-Zoubi as saying the government needs more details before making a decision on whether to participate in the conference.
He also said Syria will not take part in any dialogue that infringes on its sovereignty and insisted that Mr. Assad's fate is a matter only for the Syrian people to decide at the ballot box.
French Foreign Minister Laurent Fabius acknowledged that diplomatic efforts to bring Syria's warring parties together are "very difficult." He said the two sides have to agree on negotiators who do not have "blood on their hands" from the conflict, which has killed more than 80,000 people.
Russian President Vladimir Putin said it is extremely important for all parties to avoid actions that could aggravate the situation in Syria. He made the comment after talks with Israeli Prime Minister Benjamin Netanyahu Tuesday in the Russian resort of Sochi.
Mr. Netanyahu said he and Mr. Putin are trying to find ways to strengthen stability and security in the Middle East by explaining their positions to each other "directly" and "openly."
Israel and the United States have expressed concern about planned Russian sales of advanced anti-aircraft weapons to Syria. Such weapons would complicate potential Israeli or Western air strikes against President Assad's forces.
Russian Foreign Minister Sergei Lavrov said last week his government is completing arms sales to Syria under existing contracts, but he did not say if advanced S-300 missile batteries were included.
In another development, a gruesome YouTube video apparently showing a rebel mutilating the body of a Syrian solder has drawn condemnation from human rights and Syrian opposition groups.
New York-based Human Rights Watch said the video posted on Sunday shows the commander of a Syrian rebel brigade, Abu Sakkar, cutting out and biting the heart of the dead soldier. The rebel also hurls sectarian insults against Alawites, the minority Syrian sect of President Assad.
Human Rights Watch said it is not clear if the brigade operates within the command structure of Syria's main rebel coalition, the Free Syrian Army.
But, it called on the Free Syrian Army and its exiled political wing, the Syrian National Coalition, to hold those responsible for war crimes accountable and prevent such abuses by anyone under their command.
The Syrian National Coalition said it "strongly condemns this act - if it is revealed to be true." The group said the mutilation "contradicts the morals of the Syrian people" and the "values" of the Free Syrian Army. It promised to eventually try the culprit in front of an "honest and fair judiciary."