Russia has given a "general list" of goods on its relief convoy to Ukrainian authorities and the International Committee of the Red Cross, but the aid agency has demanded a more detailed inventory.
The independent agency has been holding talks with Ukrainian and Russian authorities on delivering Russia's proposed aid to eastern Ukraine, but on Monday laid down strict guidelines to uphold its neutral role in conflicts.
"The Russian authorities have shared a general list of items with the Ukrainian authorities and the ICRC. The list includes basic necessities such as water bottles, food items, as well as generators," ICRC spokeswoman Anastasia Isyuk said Wednesday.
"A detailed inventory of the contents of the trucks is needed for the ICRC to receive this aid, once it has been officially cleared by Ukrainian border officials."
Russia said Wednesday suggestions it could use the humanitarian aid convoy to Ukraine as a cover for invasion were absurd.
The UN said the death toll in fighting had doubled in the last two weeks to over 2,000.
"A number of important issues still need to be clarified between the two sides, including border crossing procedures, customs clearance and other issues," Isyuk said.
The situation was changing by the hour and the ICRC could not provide further details on how the operation could take place, she said.