Zurich - The prospects for launching Syria peace talks next week hung in the balance on Wednesday after a meeting between the top US and Russian diplomats ended in Zurich without a hint that the two sides have agreed upon which groups should participate.
Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov met for three hours at Zurich's airport to bridge differences about which factions should negotiate with Syrian government representatives at the peace talks scheduled to start Monday in Geneva.
"We have provided our proposal, the US did the same, and now the members of the Syria opposition groups also provided their proposal" on the invitation list, Lavrov told reporters, stressing that it was now up to UN Syria envoy Staffan de Mistura to come up with a solution.
Contrary to Washington's position, Lavrov reiterated that the armed Islamist groups Jaish al-Islam and Ahrar al-Sham should not be invited. He labelled them as terrorist organisations.
In addition to the participation issue, Moscow and Washington also disagree on the future of Syrian President Bashar Assad, who has lost all legitimacy in the eyes of the US administration.
Lavrov did not say whether he believed the UN-brokered peace talks between the Syrian government and opposition could start on Monday in Geneva as planned, but he said the US and Russia agreed that "these negotiations will start as soon as possible."
US and Russian officials have not ruled out that the Geneva peace talks will have to be postponed.
As Kerry met Lavrov, the mainstream Syrian opposition alliance accused Russia of hampering the talks by trying to dictate who would represent the opposition.
According to a recent report in the pan-Arab newspaper Al Hayat, Russia has requested that Syrian Kurdish forces and Damascus-based politicians seen by their opponents as close to the government be represented in the opposition delegation.
Kurdish-led forces who control much of northern Syria and have received extensive US air support have also demanded a seat at the table.
The Syrian opposition alliance formed to take part in the peace talks, meanwhile, warned it would not participate if any "third party" was invited.
Russia was obstructing the talks by "imposing a list of names on the opposition delegation", Riad Hijab, the co-ordinator of the opposition alliance, said after a meeting in the Saudi capital Riyadh to determine the members of its delegation.
The alliance announced that its delegation would be headed by Asaad al-Zoubi, a former air force general who defected to the opposition, and would include both military and political figures.
The hardline Islamist Jaish al-Islam, also known as Army of Islam, will be represented by Mohammed Alloush, cousin of its late leader Zahran Alloush, sources close to the opposition leadership said.
Ahrar al-Sham, arguably the strongest rebel force in military terms, will not be directly represented, but will have members "behind the scenes" in Geneva, the sources told dpa.
In the Zurich talks, Kerry pressed Lavrov to use Russia's influence with the government of Assad and secure humanitarian access to the many Syrians in besieged and inaccessible areas, the US State Department said in a statement from Washington.
Kerry travelled to the Swiss mountain resort of Davos after meeting Lavrov to attend the World Economic Forum, where he was expected to discuss the Syria crisis with other diplomatic leaders.
More than 250 000 people are estimated to have been killed in Syria's conflict since it started in 2011 and developed into a war involving government forces, opposition rebels, Islamist extremists and Kurdish units, according to the United Nations.