Investigative journalist Carl Bernstein rebuked President Donald Trump for his behavior amid the ongoing Russia probe in which federal prosecutors are examining the Trump campaign's ties to Russian operatives who meddled in the 2016 US election.

Bernstein said in an interview this week, "the Trump presidency is worse than Watergate," because of open attempts by the president and his allies to damage some of the long-standing pillars of the US government.

"The system worked in Watergate," Bernstein said, adding that now, Trump's loyalists in Congress "have done almost anything they can to impede and undermine legitimate investigation."

In the 1970s, Bernstein helped uncover the Watergate scandal that ultimately led to the resignation of President Richard Nixon.

Carl Bernstein, the veteran journalist who helped uncover the 1970s Watergate scandal that led to the resignation of President Richard Nixon, says Donald Trump's presidency "is worse than Watergate."

Bernstein's remarks during a CNN interview this week were a rebuke of Trump's behavior amid the ongoing Russia investigation. Trump has escalated his attacks on the probe in which federal prosecutors are examining his campaign's ties to Russian operatives who meddled in the 2016 US election.

Investigators are also looking into whether the Trump campaign colluded with the Russians to help him get elected, a question Trump frequently rejects.

During his interview on CNN, Bernstein was asked if Nixon, who was a subject of the Watergate scandal in the 1970s, behaved as anxiously then as Trump is behaving now.

"I think what we're seeing is more than anxiety on the part of Donald Trump," Bernstein said. "We are seeing a president who is behaving and acting unhinged."

Bernstein pointed to Trump's frequent lashing out at the press, whom he has called "the enemy of the American people." He said Trump has "whipped up a kind of hysteria" around the journalists and news organizations who cover him.

Bernstein also asserted that Republicans in Congress have faltered in ways that Republicans in the Nixon-Watergate era did not.

"The heroes of Watergate were Republicans who demanded that the president be held accountable," Bernstein said. They "demanded he be transparent, to know what did the president know and when did he know it, and who conducted bipartisan investigations that led to understanding and finding out what Nixon had done."

Bernstein continued, chastising the current crop of Republicans on Capitol Hill whom he says have "done almost everything they can to impede and undermine legitimate investigation," referring to conservative members of the House GOP who have accused the FBI and Justice Department of harboring political biases against Trump.

We're in "a totally different and much more dangerous situation," Bernstein said.

"Donald Trump is a demonstrable authoritarian in terms of his rhetoric, in terms of whipping up his base. Nixon did not do anything similar to that."

Watch Bernstein's remarks below: