The UN Security Council will hold an emergency meeting on Friday to decide whether to go ahead with air drops in Syria after the Damascus regime allowed convoys to enter two besieged towns.
Russia's Ambassador Vitaly Churkin welcomed the aid deliveries as a positive step and suggested that plans to air drop humanitarian relief could be put on hold for now.
Britain on Wednesday called for the special meeting to discuss humanitarian access and press ahead with the air drops decided at a meeting last month of the 20-nation International Syria Support Group (ISSG).
"It's too little, too late," said British Ambassador Matthew Rycroft. "I think that we need to press on with what the ISSG said, which is in that scenario there needs to be air drops."
The ISSG set June 1 as the deadline for aid convoys to reach all besieged areas or else the United Nations would begin air drops of assistance.
An aid convoy earlier Wednesday entered the town of Daraya for the first time since 2012 and a second delivery reached Moadamiyeh for the first time since March.
Both towns are besieged by Syrian forces.
"It's a positive step," Churkin told reporters. "Air drops are much more complicated and much less effective and so I think we need to continue to pursue with land deliveries."
According to the UN, a total of 592,000 people live under siege in Syria — the majority besieged by regime forces — and another four million live in hard-to-reach areas.
Peace talks to end Syria's five-year war stalled in April after the opposition walked out over escalating fighting on the ground and lack of humanitarian aid.
Syria's devastating civil war has killed more than 280,000 people.
AFP contributed to this report.