The special counsel, Robert Mueller, sent a document preservation request to the White House, saying the June 2016 meeting that Donald Trump Jr. had in Trump Tower in New York is relevant to his investigation, the source said on Friday.
The White House counsel's office relayed the request, a routine part of the early phase of any investigation, to other members of the White House staff on Wednesday, the source said.
News earlier this month of the meeting between Trump's eldest son and a Russian lawyer he was told had damaging information about his father's presidential rival, Democrat Hillary Clinton, fuelled questions about the campaign's dealings with Moscow. The Republican president has defended his son's meeting as simple politics.
Mueller, appointed by the Justice Department in May, is probing U.S. intelligence agency allegations that Russia interference in the election and potential collusion by Trump's campaign, an issue that has engulfed the six-month-old administration.
Trump has long expressed frustration with a probe that he has called a political witch hunt, and has denied any collusion. Moscow has denied it interfered in the election campaign to try to tilt the November 2016 vote in Trump's favour.
Document requests of the type sent by Mueller generally cover emails, text messages, voicemails, notes or records. The counsel is looking for any indication that the president knew the meeting his son had was planned and might have suggested topics for discussion, the source said.
He would also be inquiring into whether Trump was briefed on the meeting afterward, as well as what was discussed, the source said. Mueller would be interested, the source said, in topics such as any discussion of U.S. economic sanctions on Russia, possible Russian investments in the United States or elsewhere, or a possible lifting of a Russian ban on Americans adopting Russian children.
Russia imposed the adoption ban to retaliate for the 2012 Magnitsky Act, which imposed sanctions on Russian individuals to punish Russia for human rights violations.
WAYS OF LIMITING PROBE
Newspaper reports said Trump's lawyers are reviewing ways to limit or undermine the special counsel.
The Washington Post and The New York Times on Thursday cited unidentified people familiar with the strategy. A Trump attorney contacted by Reuters, John Dowd, denied the reports and praised Mueller. "We think he's a straight, honest guy," Dowd said.
Dowd said communications with Mueller were productive and "we have confidence he's going to do the right thing."
Senior White House advisor Kellyanne Conway referred on Friday to reports that members of Mueller's team have made donations to the Democratic Party. "People should know what folks' paths and motivations and political motivations are," she said in a Fox News interview.
According to the Post, Trump has asked his advisers about his power to pardon aides, family members and even himself in connection with the Russia probe. Trump's lawyers have been discussing the president's pardoning powers, a second person told the newspaper.
Dowd dismissed the pardon report as nonsense. "It's just not true," he said.
In an interview with the New York Times on Wednesday, Trump suggested the special counsel's remit should be limited, warning Mueller against investigating his and his family's finances, which he said are unrelated to the Russia investigation.
The Republican president also hinted at possible conflicts of interest involving Mueller, a former FBI director who is popular among Republicans and Democrats.
Republican U.S. Representative Michael McCaul told MSNBC on Friday that "it seems paranoid" for Trump to go after Mueller, calling Mueller a man of integrity with bipartisan support who needs to be allowed to do his work.
Adam Schiff, the top Democrat on the U.S. House of Representatives intelligence panel, said in a statement, "Mueller has the authority to investigate anything that arises from his investigation into the Trump campaign's ties to Russia, including financial links."
His committee is one of several congressional panels investigating the Russia matter alongside Mueller's probe.
Separately, the spokesman for Trump's legal team, Mark Corallo, confirmed his resignation on Friday. Lead attorney Marc Kasowitz will take on a reduced role on the outside legal team, according to media reports.
Other recent changes included the hiring of veteran Washington lawyer Ty Cobb to a White House job to handle responses to the Russia probe.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)