WASHINGTON - US President Donald Trump's son-in-law, Jared Kushner, is willing to cooperate with federal investigators looking into ties between Russia and the Trump campaign, his attorney said.

The statement from attorney Jamie Gorelick was issued on Thursday amid reports that the FBI was investigating meetings Kushner had in December with Russian officials.

"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," the statement said.