Russia's defence ministry says 63 of its soldiers have been killed by a Ukrainian strike on a facility in the eastern Donetsk region where military personnel was stationed.

Ukrainian forces fired six rockets from a HIMARS launch system and two of them were shot down, a Russian defence ministry statement said Monday.

The strike, using a US-supplied precision weapon that has proven critical in enabling Ukrainian forces to hit key targets, delivered a new setback for Russia which in recent months has reeled from a Ukrainian counteroffensive.