Famed Watergate journalist Carl Bernstein says that the investigation into former National Security Advisor Michael Flynn could end up revealing a “cover-up” of alleged connections between President Donald Trump's team and Russia.

“There, he is central to what the FBI believes is a cover-up going on among people close to the president of the United States about what happened with the Trump campaign and Russia,” Mr Bernstein, who is now a CNN commentator, said. "The FBI, the congressional investigators are trying to learn what happened. And Flynn is almost like the ball of yarn that begins to unspool and is key to understanding it."

Mr Bernstein said that Deputy Attorney General Rod Rosenstein, now that he is leading the Justice Department's probe into Russia's role alleged in the election, will eventually see that there is a cover-up as well.

"He is going to see, ‘Oh my god, there’s a cover-up going on,’" Bernstein said.

The comments came just a day after a bipartisan press conference in which the top members of the House Oversight Committee said that Mr Flynn likely violated the law by failing to disclose foreign connections and payments when applying for a security clearance.

Representative Jason Chaffetz, the chairman of the committee, said that he had seen no indicator that the disgraced national security adviser disclosed a $45,000 payment he had received from Russian state-owned television network RT for giving a speech. Mr Flynn also appeared to have received more than $500,000 for representing the Turkish government.

“I think it's obvious that Gen. Flynn is in up to his neck in terms, not just of possible crimes involving his speeches and whether or not he registered as a foreign agent, which he should have and didn’t,” Mr Bernstein said.

Mr Flynn was ousted from his position advising the president less than a month after taking up the post after it was discovered that he had failed to tell Vice President Mike Pence about conversations he had had with Russian officials during the presidential transition period. Mr Flynn failed to tell Mr Pence that he had discussed American sanctions imposed following the determination by American intelligence agencies that Russia was behind disruptions to the 2016 presidential election.