The announcement appears to preclude any kind of top-level meeting or breakthrough ahead of the 50-day deadline for an agreement given by President Donald Trump.

The Kremlin said on Friday that a summit between Russian President Vladimir Putin and Ukrainian President Volodymyr Zelenskiy could only happen as a final step to seal a peace deal. Kremlin spokesman Dmitry Peskov said that it was unlikely that such a meeting could occur by the end of August,

On Tuesday, Zelensky signed a law passed by the Ukrainian Verkhovna Rada (parliament) which subordinated Ukraine's two main anti-corruption agencies to the Ukrainian Prosecutor General.

Thousands of people gathered in the capital and other cities across Ukraine on Tuesday evening to urge President Volodymyr Zelensky to veto the controversial bill.

Opponents of a new law they say strips Ukraine’s anti-corruption watchdogs of their independence called for a third straight day of street protests across the country Thursday.