President Donald Trump's son-in-law and adviser, Jared Kushner, on Thursday appeared at a closed door meeting of the U.S. Senate Intelligence Committee for the second time, four congressional sources said.

It was not known what topics were discussed with Kushner, who is involved in developing an Israeli-Palestinian peace plan and has helped forged closer U.S. ties with Saudi Arabia. The committee has been conducting a largely bipartisan investigation of suspected Russian interference in the 2016 U.S. election and the nature of contacts between Trump campaign members and Russian officials, including Kushner.

A spokesman for Kushner's lawyer, Abbe Lowell, did not immediately respond to a request for comment.