A representative of the International Committee of the Red Cross is due in Moscow to discuss with Russian officials the delivery of humanitarian aid to eastern Ukraine.
Laurent Corbaz’s visit comes as Russian aid convoy is still awaiting checks near Ukraine's border.
Russia said on August 18 that agreements had been reached with Kyiv and the Red Cross that clear the way for Russian humanitarian shipments into war-torn eastern Ukraine.
Meanwhile, Ukraine said "dozens" of civilians have been killed in a rebel attack on a convoy of people trying to flee war-torn eastern Ukraine.
Reuters quoted Ukrainian military spokesman Andriy Lysenko as saying on August 19 that 15 bodies had so far been recovered.
Kyiv said the convoy was hit in the Luhansk region on August 18 despite the fact the trucks were flying white flags.
The pro-Russian separatists dismissed the reports of the attack as "pure propaganda."