(CNN) Democratic Sen. Richard Blumenthal of Connecticut says the grand jury in the special counsel's investigation into Russian meddling should "be very interested" in a 2016 meeting involving Middle East specialist George Nader, United Arab Emirates officials and members of President Donald Trump's inner circle.

"The motive in a criminal prosecution is clearly important -- particularly if it is a corrupt motive, if it involves compromising confidential information or a position of trust -- and so the grand jury ought to be very interested in what George Nader has to say about the substance of that conversation at that meeting and others involving him in other parts of the world. The special counsel probably knows -- not probably knows, but certainly knows -- more than we do, and that meeting was significant," he said on CNN's "Erin Burnett OutFront."

Nader, a low-profile diplomatic go-between with ties to Trump's team who has forged close ties to the UAE, was stopped and questioned by the FBI at Washington Dulles International Airport in January as he returned from an overseas trip, sources say. Since then, he has been talking to Mueller's investigators and providing information to the grand jury.

Nader attended a December 2016 meeting in New York between Emirati officials and members of Trump's inner circle, and another in January 2017 in the Seychelles islands between the Emiratis and Erik Prince, a Trump associate. Nader was also in the Seychelles when Prince met with a Russian banker, the sources said.

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