Peter Carr, a spokesman for the special counsel, declined to comment.
CNN reported Friday that Sanders had met with Mueller’s team and that the interview was one of the last before the special counsel’s team wraps up its investigation.
Mueller is investigating Russian interference in the 2016 presidential election, including whether any members of the Trump campaign conspired with foreign officials during the race.
Sanders did not say what the Mueller team asked her about.
While the White House has often referred questions about the Russia investigation to President Trump’s outside lawyers, Sanders has occasionally made public statements defending the president against charges that his campaign colluded with Russia to get elected.
Echoing the president, she has publicly referred to Mueller’s probe as a “witch hunt.”
The Mueller investigation has led to numerous indictments and convictions of Trump campaign associates and others, with charges including lying to investigators.
Sanders was on Air Force One in 2017 when Trump helped draft a misleading statement about Donald Trump Jr.’s 2016 meeting at the Trump Tower in Manhattan with a Russian lawyer offering political dirt on Democratic presidential nominee Hillary Clinton.
Sanders said publicly Trump did not dictate that statement. Trump’s lawyers, however, later told the special counsel that the president did dictate the statement.