An American businessman who worked for years undercover as an FBI confidential witness was blocked by the Obama Justice Department from telling Congress about conversations and transactions he witnessed related to the Russian nuclear industry's efforts to win favor with Bill and Hillary Clinton and influence Obama administration decisions, his lawyer tells The Hill.

Attorney Victoria Toensing, a former Reagan Justice Department official and former chief counsel of the Senate Intelligence Committee, said Tuesday she is working with members of Congress to see if they can get the Trump Justice Department or the FBI to free her client to talk to lawmakers.

"All of the information about this corruption has not come out," she said in an interview Tuesday. "And so my client, the same part of my client that made him go into the FBI in the first place, says, 'This is wrong. What should I do about it?'"