WASHINGTON—Former acting Attorney General Sally Yates has been interviewed by Special Counsel Robert Mueller’s investigators about her meetings with White House officials, and she recounted concerns she had shared with the Trump administration about former national security adviser Mike Flynn, according to people familiar with the matter.

The interview in July suggests that Mr. Mueller and his team are interested in uncovering what White House officials knew about the Federal Bureau of Investigation probe into Mr. Flynn that preceded the appointment of the special counsel. They have also signaled their interest in whether that knowledge among White House officials influenced President Donald Trump in his interactions with the bureau’s former director, James Comey, information that could be relevant to an obstruction-of-justice case, the people said.

A spokesman for the special counsel’s office declined to comment. Ms. Yates, a former deputy attorney general in the Obama administration, also declined to comment, saying in an email she was “going to let my Senate testimony do the talking for now.” She appeared in May before a Senate Judiciary subcommittee investigating alleged Russian election interference.

Ms. Yates’s interview with the special counsel covered a range of topics, people familiar with the matter said. But it takes on added significance in the wake of Mr. Flynn’s recent guilty plea for lying to FBI agents. Mr. Flynn admitted he falsely told agents he hadn’t discussed sanctions with the Russian ambassador or urged a Russian vote against a pending United Nations resolution, when he had done both.

Mr. Flynn is now cooperating with Mr. Mueller’s investigation, which Mr. Trump has called a “witch hunt.” Moscow has denied interfering in the election. Mr. Flynn resigned Feb. 13 after it emerged he had misled the Vice President Mike Pence about the nature of his conversations with Sergey Kislyak, then the Russian ambassador to the U.S.