WASHINGTON (AP) - Special counsel Robert Mueller told Attorney General William Barr that Barr's summary of the Russia probe's findings caused "public confusion about critical aspects" of the investigation.

A copy of Mueller's letter to Barr was released Wednesday.

In his letter, Mueller raised concerns about a letter that Barr sent to Congress detailing what he said were Mueller's principal conclusions. Mueller said Barr's letter "did not fully capture the context, nature and substance" of the special counsel's work and conclusions.

Barr's letter was released just two days after the Justice Department received the special counsel's report. It said Mueller hadn't reached a conclusion on whether the president had obstructed justice despite presenting evidence on both sides of the question.

Mueller's letter is likely to be a central focus at Wednesday's Senate Judiciary Committee hearing with Barr. Barr's prepared testimony shows he plans to defend his handling of Mueller's report.