The deal to avoid a Syrian government offensive on Idlib province is still being worked out by Russia and Turkey, the UN said Thursday, stressing that the threat to civilians remained high.
"This is not a peace deal. It is an aversion of (a) whole-scale-war deal," the head of the United Nations Humanitarian Taskforce for Syria, Jan Egeland, told reporters in Geneva.
Syrian government ally Russia and rebel supporter Turkey reached an agreement to create a demilitarised buffer zone in Idlib, Syria's last opposition bastion, where half of its three million residents have been displaced from areas retaken by Syrian forces.
While briefing the taskforce about the pact on Thursday, Russian and Turkish envoys made clear they "are still working... on the details," Egeland said.
He expressed hope it was an indication that "the big war was averted" in Idlib, although Russia stressed it would continue operating against fighters it identifies as terrorists.
"I see a great potential for a lot of fighting," Egeland said. "We are concerned for the civilians in these areas, so it is not over."
The UN has repeatedly warned that a full-scale assault on Idlib could trigger the bloodiest episode of Syria's seven-year war, which has killed more than 360,000 people and displaced millions.
Despite the ongoing concerns, Egeland said he was "relieved" for now.
"The outcome here was the least bad of (the) realistic solutions," he said.