WASHINGTON — Special counsel Robert Mueller has alerted the White House that his team will likely seek to interview six top current and former advisers to President Trump who were witnesses to several episodes relevant to the investigation of Russia’s meddling in the 2016 election, according to people familiar with the request.

Mueller’s interest in the aides, including trusted adviser Hope Hicks, ex-press secretary Sean Spicer and former chief of staff Reince Priebus, reflects how the probe that has dogged Trump’s presidency is starting to penetrate a closer circle of aides around the president.

Each of the six advisers was privy to important internal discussions that have drawn the interest of Mueller’s investigators, including his decision in May to fire FBI Director James Comey and the White House’s initial inaction following warnings that then-national security adviser Michael Flynn had withheld information from the public about his private discussions in December with Russia’s ambassador to the United States, according to people familiar with the probe.

The advisers are also connected to a series of internal documents that Mueller’s investigators have asked the White House to produce, according to people familiar with the special counsel’s inquiry.

Roughly four weeks ago, the special counsel’s team provided the White House with the names of the first group of current and former Trump advisers and aides that investigators expect to question.

In addition to Priebus, Spicer and Hicks, Mueller has notified the White House he will likely seek to question White House counsel Don McGahn, and one of his deputies, James Burnham. Mueller’s office has also told the White House that investigators may want to interview Josh Raffel, a White House spokesman who works closely with Trump son-in-law Jared Kushner.

White House officials are expecting that Mueller will seek additional interviews, possibly with family members, including Kushner, who is a West Wing senior adviser, according to the people familiar with Mueller’s inquiry.

Spicer declined to comment, while Priebus did not respond to a request for comment.

Ty Cobb, a White House lawyer focused on the probe, declined to comment on behalf of current White House aides McGahn, Burnham, Hicks and Raffel. Cobb also declined to discuss the details of Mueller’s requests.

A spokesman for Mueller declined to comment.

No interviews have been scheduled.