Ukraine plans to fire the prosecutor who led investigations into the firm where former U.S. Vice President Joe Biden's son served on the board, a central figure in the activity at the heart of impeachment proceedings against U.S. President Donald Trump, a source told Reuters.

Trump's personal lawyer, Rudy Giuliani, has acknowledged meeting the prosecutor, Kostiantyn Kulyk, to discuss accusations against the Bidens.

The decision to sideline someone who played an important role in Giuliani's efforts to find out damaging information about the Bidens comes as Ukraine has tried to avoid getting drawn into a partisan fight in Washington.