President Trump's son-in-law and senior adviser, Jared Kushner, interacted with Russian Ambassador Sergei Kislyak on at least three occasions during and after the campaign, but never disclosed that they had been in communication, according to a report published late Friday.

The two men spoke at least twice by phone sometime between April and November, Reuters reported, citing unnamed sources.

However, a total of 18 undisclosed calls and emails between Trump campaign associates and Moscow-linked people took place from April to November last year. Kushner and former national security adviser Mike Flynn spoke with Kislyak in two of those calls. The other individuals have not been named.

Kushner's attorney, Jamie Gorelick, said her client does not recall speaking with Kislyak by phone between April and November.

"Mr Kushner participated in thousands of calls in this time period. He has no recollection of the calls as described. We have asked (Reuters) for the dates of such alleged calls so we may look into it and respond, but we have not received such information," Gorelick said.

Two hours earlier it was reported that Kushner had talked with Kislyak in December about creating a secret and secure communications channel between Trump's transition team and Moscow.

The duo reportedly discussed using Russian diplomatic facilities in America to keep their talks out of the public eye where U.S. intelligence officials would be able to pick up the private chats.

The new information of Kushner's older contacts with Russia indicates why the FBI is looking at him as part of its investigation into possible collusion between the campaign and Russia.