New intel may prove Trump -- not just Sessions -- had 'private encounter' with Kislyak at campaign event
President Donald Trump meets with Russian Ambassador Sergey Kislyak (Photo via Twitter).

The FBI is investigating whether President Donald Trump had an undisclosed meeting with Russian Ambassador Sergey Kislyak during a campaign event last year.

Five current and former U.S. officials tell NBC News that "they are aware of classified intelligence suggesting there was some sort of private encounter between Trump and his aides and the Russian envoy" last April at the Mayflower Hotel in Washington, D.C.

In addition to Trump, officials believe that the intelligence shows that then-Senator Jeff Sessions and Trump son-in-law Jared Kushner were also at the meeting.

The officials emphasized to NBC news that this new evidence does not yet "amount to proof" and have "declined to provide details about it."

Sessions had to recuse himself from the Russia investigation earlier this year when it was revealed that he failed to disclose two meetings with Kislyak during questioning at his Senate confirmation hearing to become attorney general earlier this year. CNN reported on Wednesday night that Sessions may have had a third undisclosed meeting with Kislyak at the Mayflower Hotel, although this report did not suggest that Trump himself was at the meeting.