The FBI is investigating meetings Donald Trump's son-in-law Jared Kushner had with Russian officials in December, according to reports.
Mr Kushner, a key White House adviser, had meetings with Moscow's ambassador to the US, Sergey Kislyak, and Russian banker Sergey Gorkov.
The Washington Post cited "people familiar with the investigation" who said the FBI investigation does not mean Mr Kushner is suspected of a crime.
His lawyer Jamie Gorelick released a statement saying: "Mr Kushner previously volunteered to share with Congress what he knows about these meetings. He will do the same if he is contacted in connection with any other inquiry."
Meanwhile, the chairman of the House oversight committee asked the FBI to turn over more documents about former director James Comey's interactions with the White House and Justice Department, including material dating back nearly four years to the Obama administration.
The FBI and the oversight committee - as well as several other congressional panels - are looking into Russian meddling in the 2016 presidential election and possible connections between Russia and the Trump campaign.
Mr Trump fired Mr Comey on May 9 amid questions about the FBI's investigation, which is now being led by special counsel Robert Mueller, a former FBI director.
House oversight committee chairman Jason Chaffetz told acting FBI director Andrew McCabe that he wants records of Mr Comey's contacts with the White House and Justice Department dating to September 2013, when Mr Comey was sworn in as FBI director under president Barack Obama.
In a letter to Mr McCabe, Mr Chaffetz said he is seeking to review Mr Comey's memos and other written materials so he can "better understand" his communications with the White House and attorney general's office.
Mr Chaffetz previously requested Mr Comey's recent memos about his private contacts with Mr Trump, but the bureau told him on Thursday it could not yet turn them over because of Mr Mueller's probe.
Mr Chaffetz, who said last week he had his "subpoena pen" ready to force Mr Comey or the FBI to turn over the documents, told Mr McCabe that "Congress and the American public have a right and a duty to examine this issue independently of the special counsel's investigation".
He added: "I trust and hope you understand this and make the right decision - to produce these documents to the committee immediately and on a voluntary basis."
The letter comes a month before he is scheduled to leave office after abruptly announcing his resignation earlier this year.
Assistant FBI director Gregory Brower told Mr Chaffetz on Thursday that the agency is evaluating his request and will update him as soon as possible.
Some Republican members of Congress have pressured Mr Chaffetz to step down from the Comey probe, saying it should be led by someone who will remain in Congress.