Scheduled peace talks in Geneva between Yemen's government and Houthi rebels hung in the balance on Thursday as the two sides traded ultimatums and a UN envoy scrambled to mediate.
The rebel delegation, still in Sanaa, insisted the UN meets three demands before it travels to Switzerland, prompting government representatives already in Geneva to give the Houthis a 24-hour deadline or threatening to leave.
UN envoy Martin Griffiths, who earlier said the planned meeting offered a "flickering signal of hope" for an end to the years-long conflict, had to postpone the start of the talks.
"He continues to make efforts to overcome obstacles to allow the consultations to go forward," his office said in a statement, adding that Griffiths remained "hopeful" the rebels would come.
The Geneva talks are meant to be the first since 2016, when 108 days of negotiations between the government of President Abedrabbo Mansour Hadi and rebels failed to yield a deal.
The Houthis control the capital Sanaa and much of northern Yemen, while a Saudi-led coalition which backs Hadi's government controls the country's airspace.
Led by Foreign Minister Khaled al-Yamani, a Yemen government delegation arrived in Switzerland on Wednesday.
But on what was meant to be the opening day of talks, the rebels issued an ultimatum from Sanaa, saying they would not join until the UN meets three conditions that it had already agreed to.
They want the transportation of wounded rebels to Oman for medical care, the repatriation of rebels who have already received treatment there, and a guarantee that the Houthi delegation will be allowed to return to Sanaa after the Geneva talks.
The government delegation said Thursday it would wait only until midday on Friday.
"We have this scheduled meeting since two months ago ... Today we are alone," delegation member Hamza Alkamali told journalists in Geneva, and claimed the rebels clearly "don't want peace".
Clearance for a flight carrying rebel delegates and wounded was "issued three days ago," he insisted.
"We want them to come, and we are pushing them to come," Alkamali said. However, "we will leave, if they don't come... in the next 24 hours.
Griffiths, was "mindful of the challenges associated with bringing the parties together to Geneva, bearing in mind that they haven't met for two years," his office said in a statement.
On Thursday, an AFP journalist saw the envoy entering the Geneva hotel hosting the Yemen government delegation.
Griffiths had told journalists he would begin informal consultations with the government team while the rebels make their way to Switzerland.
If and when the two parties do eventually meet, he said, there would be no "formal negotiations", merely exploratory talks on how best to get everyone around a negotiating table.
The UN Security Council this week urged both sides to "take a first step towards ending a conflict that has brought severe pain and humanitarian suffering to the Yemeni people".
All previous attempts to resolve the Yemen war have failed.
Griffiths is the UN's third Yemen envoy since 2014, when Houthis overran the capital and drove Hadi's government into exile.
The following year, Saudi Arabia and its allies formed a powerful regional military coalition to back Hadi.
The conflict has left nearly 10,000 people dead and pushed the Arab world's most impoverished country to the brink of famine.
On Thursday, the Saudi-led coalition acknowledged there may have been "collateral damage" from August 23 strikes the UN said killed 26 children south of the port of Hodeida.
On Wednesday, Saudi Arabia shot down a ballistic missile fired by Houthi rebels, with shrapnel wounding 26 people including two children, the coalition said.