The Russian army has been given orders to broaden its offensive in Ukraine "from all directions" after Kyiv refused to hold talks in Belarus, the defence ministry said Saturday.

Russian forces have made thrusts into the Ukrainian capital Kyiv before falling back to the outskirts, facing tough resistance on day three of the invasion ordered by President Vladimir Putin.

"After the Ukrainian side rejected the negotiation process, today all units were given orders to develop the advance from all directions in accordance with the operation's plans," Russian army spokesman Igor Konashenkov said in a statement.

The Kremlin said Friday that Putin was ready to send a delegation to Belarus for talks with Ukraine but Ukraine wanted talks in Warsaw instead.