"It's very important for the UN certainly and for everyone here to engage the Arab countries. So what I intend is to certainly to brief the Arab countries," de Mistura said.
He said the briefing would ensure that the Arab states "are feeling comfortable and understanding what Astana was about and what it could be, and in terms of reducing the danger [for] the cessation of hostilities."
The second day of Astana talks on Syria's crisis settlement ended Tuesday with Russia, Iran and Turkey agreeing on the establishment of a trilateral mechanism to monitor the ceasefire in effect since late December.
De Mistura said the format of intra-Syrian talks expected early next month will be determined after talks with UN Secretary-General Antonio Guterres and the Security Council.
"I'm going to New York to see the Secretary-General, Antonio Guterres, and the Security Council in order to report about the Astana meeting… and ask their own advice on how to proceed on the next talks," he said.