The details of a US-Russian deal on Syria, which came into effect on Monday, will be the focus of an urgently called UN Security Council meeting on Friday, diplomats said.
Council members will meet for the closed-door consultations called as a UN aid convoy was blocked and denied entry at the Syrian border.
Under the deal, all sides agreed to allow deliveries of food, medicine and other basic supplies to the war stricken Syrian city of Aleppo.
Although the deal came into effect on Monday, humanitarian aid has yet to reach the most deprived areas.
Once the ceasefire holds and the aid is delivered, the United States and Russia are set to being cooperating in jointly targeting DAESH terrorists in Syria.
Russia is a key ally of the Assad regime and is pushing for the UN Security Council to endorse the agreement, but France and other council members have stated that they first need to learn more details about the deal.
During a high-level meeting on Wednesday, Russian Ambassador Vitaly Churkin said the council could adopt a resolution backing the agreement.
US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov are due to attend the council talks, held on the sidelines of the UN General Assembly meeting.
US President Barack Obama was due Friday to meet with top national security aides in Washington to discuss the shaky ceasefire and assess prospects for the latest effort to end the five-year-long Syrian civil war.
Earlier on Thursday, the UN special envoy for Syria said that the cessation of hostilities had held out and urged the Syrian regime to issue letters authorising the delivery of aid to besieged areas in Aleppo.