Two US intelligence leaders told Congress Wednesday they were never pressured by the White House, as they were grilled on reports that President Donald Trump urged them to help ease an FBI probe into an aide's Russia ties.

"I have never been pressured, I've never felt pressure to intervene or interfere in any way with shaping intelligence in a political way or in relationship to an ongoing investigation," Director of Intelligence Dan Coats told the Senate Intelligence Committee in a closely watched public hearing.

Both Coats and National Security Agency chief Mike Rogers declined to discuss any private conversations they had with Trump, with Rogers saying he has "never been directed to do anything I believe to be illegal, immoral, unethical or inappropriate."