DAVOS/GENEVA: Syrian peace talks will go ahead in Geneva, U.S. Secretary of State John Kerry insisted Thursday, but with just days to go, rival camps bickered about who should be invited to take part.

Kerry conceded that the timetable may slip from a planned Jan. 25 start but there would be no fundamental delay, he said, and U.N. Syria envoy Staffan de Mistura would send out invitations Sunday.

“What will happen is on Monday, there will be some discussions [in Geneva], but I would say that by Tuesday and Wednesday people will be able to get there. We just see this is as logistical,” Kerry told journalists at a roundtable discussion in Davos.

“We are just kind of lining pieces up a little bit here. So we’ll see where we are.”

With no military solution in sight after almost five years of war and over 250,000 deaths, Kerry and Russian Foreign Minister Sergey Lavrov agreed Wednesday that the talks should go ahead despite no apparent agreement on who should represent the opposition.

Kerry said initial talks would be “proximity talks,” not a face-to-face meeting of participants in the same room.

“You are not going to have a situation where they are sitting down at the table staring at each other or shouting at each other; you are going to have to build some process here, and that’s what will begin.”

Countries backing the talks, including the United States, Russia, Saudi Arabia, Iran and Turkey, are still at odds over which fighting groups should be branded “terrorists,” a discussion that is expected to continue even as de Mistura shuttles between rival delegations in Geneva.

Russia and Iran, which support President Bashar Assad, have rejected attempts by Saudi Arabia, which like the United States and European powers opposes him, to organize the opposition’s delegation for the talks.

Russia wants the opposition negotiating team expanded to include other figures that could be deemed closer to its own thinking as well as the main Syrian Kurdish party, the PYD, and the affiliated YPG militia. But the opposition has said it will boycott the Geneva negotiations if Russia insists on such a shake-up.

Among Russia’s objections is the inclusion of Mohammad Alloush as chief negotiator for the opposition.

He is a member of the political bureau of Jaish al-Islam, a major rebel faction which Russia considers a terrorist group, and – diplomats say – is a close relative of Zahran Alloush, killed in a Russian airstrike.

But many of Assad’s foes view Jaish al-Islam as a legitimate part of the opposition.

Alloush insisted the Syrian government must halt attacks on civilians and end blockades before the talks can go ahead.

“The session will not take place until the measures are implemented ... While no measures are taken, the chances are zero,” he told Reuters.

Turkish Prime Minister Ahmet Davutoglu, speaking at the World Economic Forum in Davos, accused Russia of jeopardizing the talks by insisting on the inclusion of “terrorist groups” such as the YPG.

“Some circles, including Russia, they want to spoil the opposition side, putting some other elements in the opposition side like the YPG, which has been collaborating with the regime and attacking the moderate opposition,” he said.Iran’s foreign minister has said that 10 opposition delegates were members of Al-Qaeda – one of three groups he said must be barred.

A French diplomat said there must be a credible framework before the talks could take place and if more time was needed, the U.N. should consider it.

“What we don’t want is to repeat the previous experience of Geneva 2,” the diplomat said, referring to negotiations in 2014 that failed after a few days.

“The Security Council is clear. U.N. Special Envoy de Mistura must work with the opposition groups constituted in Riyadh. It doesn’t seem desirable to me that there is a third force,” the French diplomat said.