Washington (CNN) Special counsel Robert Mueller's confidential report on the Russia investigation is more than 300 pages, according to a Justice Department official and a second source with knowledge of the matter.

The Justice Department official described the still-secret report as more than 300 pages, while a second official said it was between 300 and 400 pages, not including exhibits.

The page length had been a mystery in the days following the announcement that Mueller had concluded his work last Friday, as the Justice Department continually declined to comment on the page count but called it "comprehensive." Attorney General Bill Barr's four-page summary of Mueller's report provided only few details of how it is structured, describing it as "divided into two parts."

Even many members of Congress have been kept in the dark about the breadth of the report until recently.

A Justice official confirmed that Barr discussed the page length on a call with House Judiciary Chairman Rep. Jerry Nadler on Wednesday. Nadler would only say the report was "very substantial" and less than 1,000 pages when asked by reporters.

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