U.S. President Donald Trump's son-in-law Jared Kushner, a senior White House adviser, is under scrutiny by the Federal Bureau of Investigation in the Russia probe, the Washington Post and NBC News reported on Thursday.

Kushner is being investigated because of his interactions with Russians, including the Russian ambassador and a banker from Moscow, the Post reported, citing people familiar with the investigation.

Kushner met in New York with Russian Ambassador Sergey Kislyak in early December and also sent a deputy to meet with Kislyak again. Trump's former national security adviser Michael Flynn also attended the early December meeting.

The Post also reports Kushner met in December with Sergey Gorkov, who heads Vnesheconombank, which has been the subject of U.S. sanctions over Russia's annexation of Crimea and its role in the war in eastern Ukraine.

The Post reports that "a former senior intelligence official said FBI agents had been looking closely at earlier exchanges between Trump associates and the Russians dating back to the spring of 2016, including one at the Mayflower Hotel in Washington."

Kushner, Kislyak and Jeff Sessions, now attorney general, attended the April 2016 event at the Mayflower where then candidate Trump delivered a speech on foreign policy.

As a presidential candidate, Trump gives a foreign policy speech at the Mayflower Hotel in Washington on April 27, 2016. The Washington Post reports there was an exchange between Trump associates and the Russians at the event. (Evan Vucci/Associated Press)

The Post says it doesn't know whether Kushner and Kislyak interacted there.

Kushner is the only current White House official known to be considered a key person in the probe, the newspaper reported. The FBI, several congressional committees and a special counsel appointed by the Justice Department are looking into allegations of meddling by Russia in the 2016 U.S. election and possible ties between Trump's presidential campaign and Russian officials seeking to influence the election.

Trump and Russia deny any collusion

The controversy has engulfed Trump's administration since he fired FBI Director James Comey on May 10.

Moscow has repeatedly denied the allegations and Trump denies any collusion with Russia.

The interest in Kushner does not mean investigators suspect him of a crime or intend to charge him, the officials told NBC News.

Officials said Kushner is in a different category from Flynn and former Trump aide Paul Manafort, the network reports. They are formally considered subjects of the investigation.

It is not known whether Kushner has received any requests from the FBI for records, NBC News said.

One of Kushner's attorneys, Jamie Gorelick, said in a statement her client would co-operate with the investigation. "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," Gorelick said. Kushner has also agreed to appear before the Senate intelligence committee.

The FBI and the White House did not immediately respond to a request for comment.

Also on Thursday, House oversight committee chairman Jason Chaffetz told acting FBI director Andrew McCabe that he wants records of fired FBI director James Comey's contacts with the White House and Justice Department dating to September 2013, when Comey was sworn in as FBI director under President Barack Obama.

In a letter to McCabe, Chaffetz said he is seeking to review Comey's memos and other written materials so he can "better understand" Comey's communications with the White House and attorney general's office.

Chaffetz, a Republican, previously requested Comey's recent memos about his private contacts with Trump. But the bureau told him Thursday it could not yet turn them over because of Mueller's probe.

Chaffetz told McCabe that "Congress and the American public have a right and a duty to examine this issue independently of the special counsel's investigation."

Assistant FBI director Gregory Brower told Chaffetz on Thursday the agency is evaluating his request and will update him as soon as possible.