WASHINGTON -- Donald Trump Jr. refused to tell lawmakers about conversations he had with his father regarding a 2016 Trump Tower meeting with a Russian lawyer after emails detailing the meeting had become public, according to the top Democrat on the House intelligence committee.

Speaking to the committee behind closed doors on Wednesday as part of its investigation into Russian meddling in the 2016 election, Trump Jr. said he didn't tell the president about the meeting between Trump campaign officials and Russians when it happened and he declined to elaborate on what he ultimately told him after the meeting became public.

California Rep. Adam Schiff said that Trump Jr. said he couldn't speak about the conversations with his father this summer because of attorney-client privilege, telling the committee a lawyer was present when he spoke to his father about the June 2016 meeting and the emails that led up to it.

Schiff said that wasn't a valid excuse not to talk, saying "the presence of counsel does not mean communications between father and son are privileged."

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The Trump Tower meeting is a matter of keen interest to special counsel Robert Mueller, who is also investigating the meddling and whether there was any obstruction of justice. Trump Jr. and Jared Kushner, Trump's son-in-law, attended the meeting with several Russian operatives under the impression that they might receive damaging information about the Democratic presidential candidate, Hillary Clinton.

Mueller is also interested in the White House response to the meeting once it became public. The White House has said the president was involved in drafting an early statement saying the meeting primarily concerned a Russian adoption program, but emails later released by Trump Jr. showed he enthusiastically agreed to the sit-down with Russian lawyer Natalia Veselnitskaya and others after he was promised dirt on his father's rival. Trump Jr. later said the promised material never materialized.

Trump Jr. said during Wednesday's eight-hour interview that he spoke with President Trump's communications aide Hope Hicks as early reports of the meeting emerged, according to one person familiar with the interview. The New York Times was first to report the existence of the meeting last July, and Trump Jr. released the emails detailing the planning for it several days later.

Hicks was with the president on Air Force One while they were writing the initial statement that said the meeting primarily concerned the adoption program.

Trump Jr. also told the intelligence panel that he didn't tell his father about the 2016 meeting at the time that it happened, according to the person familiar with his interview. The person was not authorized to speak about the testimony and asked not to be identified.

Both the House and the Senate intelligence committees have been interested in the Trump Tower meeting and have interviewed several participants. The Senate Judiciary Committee is also investigating the meeting, and interviewed Trump Jr. behind closed doors in September.

In that interview, Trump Jr. cast the 2016 meeting as simply an opportunity to learn about Clinton's "fitness, character or qualifications," insisting to investigators that he did not collude with Russia to hurt Clinton's campaign.

The Senate intelligence committee also hopes to interview Trump Jr. before the end of the year.

Kushner has spoken to both intelligence committees. The panels have also interviewed Ike Kaveladze, who was at the meeting as a representative of a Russian developer who once partnered with Trump to bring the Miss Universe pageant to Moscow, and Rinat Akhmetshin, a Russian-American lobbyist. A translator who was in attendance has also spoken to congressional investigators.

Lawmakers were also expected to ask Trump Jr. about his communications with WikiLeaks during and after the campaign. Trump Jr. released messages last month that showed him responding to the WikiLeaks' Twitter account three times, at one point agreeing to "ask around" about a political action committee WikiLeaks had mentioned. He also asked the site about a rumor about an upcoming leak, and tweeted a link that the account sent him.

Also Wednesday, the House intelligence panel released a transcript of an interview last week with Erik Prince, the founder of the security firm Blackwater and a prominent Trump supporter.

According to the transcript, which was partially redacted, Prince told the panel he met a Russian with ties to President Vladimir Putin in the Seychelles islands earlier this year, but he denies he was representing Trump in the exchange.

Prince said he and Kirill Dmitriev of the state-run Russian Direct Investment Fund had a 30-minute conversation in a hotel bar Jan. 11 and discussed oil and commodity prices and how Dmitriev wished the two countries' trade relationship would improve. The meeting has captured the interest of investigators since an April report in The Washington Post that it was an attempt to establish a back-channel line of communication between Trump and Putin.

Prince denied that assertion in the interview. He also suggested intelligence officials in former President Obama's administration leaked details of the meeting.

Though the intelligence committee does not generally release transcripts of interviews, lawmakers agreed to do so in negotiations with Prince.