The UN tells the Syrian Humanitarian Task Force "You are failing"
On the ground in Ghouta, no-one is taking advantage of the five-hour daily ceasefires ordered by the Russians.
The first disintegrated rapidly on Tuesday as Syrian forces resumed attacks, and there is a lack of trust civilians will be unharmed.
The UN says five hours is not enough for aid convoys to get to the 400,000 people trapped in the region.
"The message to the 23 member states of the humanitarian task force was unusually blunt today from our colleagues in the field. You are failing to help us to help civilians in Syria," said the special advisor to the UN's special envoy for Syria, Jan Egeland.
A Syrian doctors group says 1,123 sick and wounded need immediate evacuation. Just one aid convoy has been able to get through, back in February, with aid for just 7,200 people.