The Republican and Democratic chairmen of the Senate Intelligence Committee notified federal prosecutors last year of their suspicion that several individuals, including President Trump’s family members and confidants, might have presented misleading testimony in the panel’s investigation of Russian interference in the 2016 election, people familiar with the matter said.

The list of individuals included the president’s son, Donald Trump Jr., and son-in-law, Jared Kushner, whose accounts of their pre-election meeting with a Russian lawyer were contradicted by the president’s former deputy campaign chairman Rick Gates in interviews that were part of the criminal investigation led by special counsel Robert S. Mueller III, these people said. Like others, they spoke on the condition of anonymity to discuss what remains a highly politicized and sensitive matter.

But the intelligence committee, one person said, reserved its harshest allegations for the president’s former chief strategist, Stephen K. Bannon, former campaign co-chair Sam Clovis and private security contractor Erik Prince, saying it had reason to believe all three had lied to congressional investigators — a potential felony.

The committee’s concerns were detailed in a formal letter sent to the U.S. attorney’s office in Washington, D.C., in June 2019, people familiar with the matter said. Existence of the letter was first reported by the Los Angeles Times late Friday night.

The Senate Intelligence Committee referred several individuals’ testimony to the Justice Department over the course of its 3½ -year probe, citing discrepancies in their accounts, three officials said.

The panel, which has prided itself on having pursued its investigation without the politically charged disruptions that have undermined similar probes undertaken by other congressional committees, already has issued reports affirming that the Russians worked to damage Democrat Hillary Clinton in the 2016 election while bolstering Trump. It is expected to release the final volume of its findings as soon as next week.

The committee’s referrals were signed by then-Chairman Richard Burr (R-N.C.) and Vice Chairman Mark R. Warner (D-Va.), officials said. Some letters went to Mueller, whose investigation focused not only on Russia’s activities in 2016 but also on whether anyone within the Trump campaign conspired with those efforts. Others went to the D.C. U.S. attorney’s office.

It is unclear whether the Justice Department took action on the referrals. Officials there and with the D.C. U.S. attorney’s office declined to comment.

A referral is a tip that Congress suspects a crime was committed but does not by itself spark an investigation, let alone a prosecution. Prosecutors generally view referrals from Congress with suspicion, often seeing them as partisan attempts to embarrass political opponents — although this referral was made with bipartisan agreement. Others fall short of alleging serious legal wrongdoing.

Burr acknowledged in 2018 that the panel had made criminal referrals — and that “in a lot of those cases, those might be tied to lying to us.” At the time, he said the intelligence committee had interviewed more than 200 witnesses. His office declined to comment for this report.

According to the Los Angeles Times, which viewed a copy of the referral letter, the committee told the Justice Department than Bannon may have lied about his interactions with Prince and others regarding a meeting Prince held in the Seychelles with an official close to President Vladimir Putin. Prince had told Mueller’s team that he briefed Bannon on the meeting, which occurred before Trump’s inauguration in early 2017; Bannon denied the conversation took place.

Last year, shortly after a report was released detailing Mueller’s findings, the Democrat-led House Intelligence Committee made a criminal referral to the Justice Department for Prince, accusing him of intentionally misleading the panel during its examination of the 2016 election. The Times article also notes that Clovis was referred for possibly lying about his contacts with a Republican operative spearheading an effort to obtain undisclosed emails from a personal computer server belonging to Clinton.

William Burck, a lawyer for Bannon, declined to comment, saying “it’s impossible to respond to something I’ve never heard about before.”

Victoria Toensing, a lawyer for Clovis, said: “You mean former Chairman Burr, who is under investigation for insider trading, also doesn’t know the legalities of a false statement? Mr. Clovis testified at length before the special counsel’s grand jury and was never charged. After his testimony, we never heard again from the special counsel.”

The Justice Department has been investigating stock sales Burr made before the coronavirus pandemic crashed global markets, and in recent months seized his cellphone and executed a search warrant for his electronic communications. Burr stepped down as committee chairman amid the probe.

Matthew L. Schwartz, a lawyer for Prince, noted that Prince had testified to the House Intelligence Committee in November 2017 and his testimony has been public for years. That committee made a criminal referral in April 2019. “It unsurprisingly went nowhere,” Schwartz said in a statement. “If members of the Senate likewise made a referral — which we don’t know anything about — there would be nothing new for the Department of Justice to consider, nor is there any reason to question the Special Counsel’s decision to credit Mr. Prince and rely on him in drafting its report.”

Prince, according to a person familiar with the matter, never testified before the Senate Intelligence Committee, though he provided a copy of his House testimony to that panel.

The letter sent to prosecutors last year was divided into two sections, according to two people familiar with its contents. The first named those suspected of making false statements: Bannon, Clovis and Prince.

Its second section raised concerns about other witnesses whose testimony was contradicted by Gates, though it did not pointedly make a false-statements allegation, people familiar with the letter said. In addition to Trump Jr., that section of the letter also cited Trump’s former communications director Hope Hicks and former campaign chairman Paul Manafort.

“We are fully confident in the testimony and information provided by Donald J. Trump, Jr.,” said Alan Futerfas, his lawyer. “In our view, this is a non-story.”

A lawyer for Manafort declined to comment. A representative for Kushner did not immediately respond to requests for comment. Hicks declined to comment immediately, citing a lack of familiarity with the referral.

Trump Jr., Kushner, Hicks and Manafort all either took part in or were involved in strategizing how to speak to the media about a June 2016 meeting at Manhattan’s Trump Tower with Natalia Veselnitskaya, the Russian lawyer promising damaging information about Clinton.

Trump Jr., who first sat for a lengthy interview with the Intelligence Committee investigators in late 2017 and returned under subpoena to speak with the full panel in June 2019, told investigators that he never informed his father about the Trump Tower meeting. But Trump’s former personal lawyer Michael Cohen told investigators working with Mueller that he recalled otherwise.

Cohen told Mueller’s team of being present when Trump Jr. “told his father that a meeting to obtain adverse information about Clinton was going forward,” according to a report detailing the special counsel’s findings. Cohen said he did not remember whether the meeting was connected to Russia, Mueller’s report said. He was later sentenced to three years in prison for, among other crimes, lying to Congress.

Gates, meanwhile, told Mueller’s team that he recalled that in the days before the Trump Tower meeting, Trump Jr. announced at a regular gathering of senior campaign staff and Trump family members that he had a lead on negative information about Clinton’s family foundation, according to the special counsel’s report. Among those present, Gates told Mueller, were Manafort, Hicks and Eric Trump, another of the president’s sons.

Spencer S. Hsu contributed to this report.