The UN's presence in Sochi was based on a common understanding between the United Nations and Russia on the nature and outcome of the meeting and its contribution to the Geneva process.
The Sochi talks concluded with a statement fully in line with that common understanding, Guterres told reporters at UN Headquarters in New York.
The final declaration at the Sochi talks embraced a vision of Syria for all Syrians -- as reflected by the 12 living intra-Syrian principles put forward by his special envoy for Syria Staffan de Mistura late last year, said Guterres.
The two-day Sochi talks ended Tuesday. The talks affirmed that a Constitutional Committee should be formed under UN auspices in accordance with Security Council Resolution 2254, which provides for a roadmap of political settlement of the Syria crisis that has entered into the eighth year.
The Sochi talks also made it clear that a final agreement on the mandate, terms of reference, powers, rules of procedure, and selection criteria for the composition of the Constitutional Committee is to be reached in the UN-led talks in Geneva, he said.
"My special envoy will now draw on this Sochi outcome to meet our shared goal: full implementation of Security Council Resolution 2254 and the Geneva Communique. He will also work for the talks to address the other areas determined by Resolution 2254."
Guterres, however, expressed concern over the situation on the ground. "We must never forget that progress toward a political settlement needs to be accompanied by progress on the ground."
Yet in the last two months, he said, not a single convoy of life-saving relief has reached a besieged area -- no medical supplies, no food. "Humanitarian aid is not getting in. And people suffering dire health conditions are not getting out."
He also expressed concern over "disturbing new reports" about the possible use of chemical weapons.
Guterres called on the Syrian government and opposition delegations and all countries with influence to cooperate with his special envoy. "We must ensure that the UN-led process moves ahead in Geneva, credibly and seriously."