US President Donald Trump's son-in-law and close adviser Jared Kushne, 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 told Reuters.

By early this year, Kushner had become a focus of the FBI investigation into whether there was any collusion between the Trump campaign and the Kremlin.

Kushner initially had come to the attention of FBI investigators last year as they began scrutinising former national security adviser Michael Flynn's connections with Russian officials, the two sources said.

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

The new information about the two calls as well as other details uncovered by Reuters shed light on when and why Kushner first attracted FBI attention, and show that his contacts with Russian envoy Sergei Kislyak were more extensive than the White House has acknowledged.

NBC News reported on Thursday that Kushner was under scrutiny by the FBI, in the first sign that the investigation, which began last July, has reached the president's inner circle.

The FBI declined to comment, 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 Kushner and Flynn had met Kislyak at Trump Tower in December to establish "a line of communication."

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 Kushner and Russian officials.