Russia was moving forces from northern to eastern Ukraine to try to encircle Ukrainian troops but was keeping some near the capital Kyiv to tie down part of the Ukrainian military there, a Ukrainian presidential adviser said on Wednesday.

Russia has not responded to the claim.

Speaking on national television, Oleksiy Arestovych also mentioned Ukraine had improved its negotiating position since the start of the Russian invasion on February 24, pushing to secure neutral status but with external security guarantees.

(With input from Reuters)