Mueller's Special Counsel's Office will make public an indictment on Monday, a U.S. official with firsthand knowledge of the process confirmed to NBC News, without disclosing the name of the target or the nature of the charges. The timing was confirmed by a second source familiar with the matter.

CNN was the first to report on Friday that the grand jury approved charges, citing multiple sources. The network added that the charges remain sealed by order of a federal judge.

Peter Carr, a spokesperson for Mueller, declined to comment Friday night.

Mueller, a former FBI director, was appointed in May as special counsel to oversee the investigation into alleged Russian interference in the election.