The UN Security Council will hold an urgent meeting on Friday to hear details of a US-Russian deal on Syria as it weighs whether to endorse the agreement, diplomats said.
Council members will meet at 5:30 pm (2130 GMT) for the closed-door consultations called as a UN aid convoy was blocked at the Syrian border.
Under the deal, all sides were due to allow deliveries of food and other basic supplies to the battleground city of Aleppo after a ceasefire went into effect on Monday.
Once aid is delivered and the ceasefire holds, the United States and Russia were to begin cooperating in jointly targeting Islamist rebel fighters in Syria.
Russia, Syria's key ally, is pushing for the Security Council to endorse the agreement, but France and other council members have said they first need to learn more details about the deal.
Russian Ambassador Vitaly Churkin said the council could adopt a resolution backing the agreement during a high-level meeting on Wednesday.
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 gather top national security aides in Washington to discuss the shaky ceasefire and assess prospects for the latest effort to end the five-year war.