Donald Trump has hit out at a "hoax" as it was revealed his son-in-law Jared Kushner would be interviewed by the Senate committee investigating meddling by Russia in last year's US election.

Mr Kushner, a senior adviser to the president, will be the first person in the White House, and the closest to Mr Trump, to appear before the Senate Intelligence Committee to be asked about meetings with Russian officials.

He met once with the Russian ambassador, and once with the head of a Russian bank, during the transition period between Mr Trump's election victory in November and his inauguration in January.