Some of the trucks sent to Ukraine - in a Russian aid convoy - are now returning to Russia.
It comes as German Chancellor Angela Merkel arrived in Kiev for talks with Ukraine's pro-Western leaders on the ongoing conflict.
The convoy of more than 200 vehicles had entered the country without the permission of the Ukraine government.
OSCE monitors say an unspecified number of trucks have now left - while Russian news agencies are reporting that 34 have arrived back at the border after unloading their cargo in rebel-held Luhansk.
The UK's Ambassador to the UN, Sir Mark Lyall-Grant, says no agreement was reached with the Russians.
