US President Donald Trump’s son-in-law and two eldest sons have faced scrutiny from the FBI in its ongoing investigation into Russia’s interference in the 2016 election.

It has been revealed Jared Kushner, who is married to Mr Trump’s daughter Ivanka, had at least three previously undisclosed contacts with the Russian ambassador to the United States during and after the 2016 presidential campaign.

Those contacts included two phone calls between April and November last year, current and former US officials have told Reuters.

Mr Kushner’s attorney, Jamie Gorelick, said Kushner did not remember any calls with Kislyak 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,” she said.

This revelation came as ABC News in the United States reported Mr Trump’s two eldest sons, Donald Jr and Eric, were summoned for an emergency session with the FBI over cybersecurity issues.

Mr Kushner has been a focus of the FBI investigation into whether there was any collusion between the Trump campaign and the Kremlin since earlier this year.

He initially came to the attention of FBI investigators last year when they began scrutinising former national security adviser Michael Flynn’s connections with Russian officials, sources told Reuters.

On Thursday, NBC News reported Mr Kushner was under scrutiny by the FBI – the first sign the investigation, which began last July, had reached the president’s inner circle.

In response, his lawyers said Mr Kushner would cooperate fully with the FBI.

“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,” his legal team said in a statement.

But the new information about the two calls sheds light on when and why Mr Kushner first attracted FBI attention, and show that his contacts with Russian envoy Sergei Kislyak were more extensive than the White House has acknowledged.

While the FBI is investigating Mr Kushner’s contacts with Russia, he is not currently a target of that investigation, the current law enforcement official said.

The FBI declined to comment on Mr Kushner’s involvement in the investigation, while the Russian embassy said it was policy not to comment on individual diplomatic contacts. The White House did not respond to a request for comment.

In March, the White House said that Mr Kushner and Mr Flynn had met Kislyak at Trump Tower in December to establish “a line of communication.”

Mr Kislyak also attended a Trump campaign speech in Washington in April 2016 that Kushner attended.

The White House did not acknowledge any other contacts between Mr Kushner and Russian officials.

Donald Jr (left) and Eric Trump have reportedly attended a meeting with the FBI. Photo: Getty

Eric and Donald Jr Trump have also been under the microscope, with sources revealing to ABC News the two men met FBI cybersecurity experts and CIA representatives on May 8 to discuss an attempted overseas cyberattack against the Trump Organisation.

This meeting came a day before Mr Trump fired FBI director James Comey, citing a “loss of confidence” in him.

When contacted by the ABC, Eric Trump denied the Trump Organisation had been hacked, but would not deny he and his brother had attended a meeting with the FBI.