Satellite images show a 40-mile long convoy of Russian military vehicles near the Ukrainian capital.
Airstrikes have also been carried out on an airbase on the edge of Kyiv.
The first round of talks between the two sides have ended without agreement.
Meanwhile, the UN says more than half a million people have now fled Ukraine into neighbouring countries.
Moscow could be facing a war crimes investigation by the International Criminal Court.
Prosecutors are looking into suggestions its forces appear to have used indiscriminate cluster munitions against civilian areas.
Ukraine’s ambassador to the UN has shared what he says is a text message from a Russian soldier to his mother.
Sergiy Kyslytsya says it was sent just before he was killed…………
