One of the reporters who helped expose Richard Nixon's involvement in the Watergate scandal has claimed that Donald Trump's attacks on the press "are more treacherous" than those of his predecessor.

Carl Bernstein, whose expose of clandestine and often illegal activities undertaken by members of the Nixon administration with Bob Woodward led to the US leader's 1974 resignation, said that Mr Trump's choice of language brought to mind “dictators and authoritarians, including Stalin, including Hitler”.

“Trump's attacks on the American press as 'enemies of the American people' are more treacherous than Richard Nixon's attacks on the press,“ former Washington Post reporter told CNN.

While Mr Nixon tended to attack his enemies in private, Mr Trump regularly broadcasts his views on the press to his 25 million Twitter followers, Mr Bernstein said.

He added that Mr Trump's rhetoric is potentially more dangerous than Mr Nixon's attacks on the news media because it is more public.

“There is no civic consensus in this country like there was at the time of Watergate about acceptable presidential conduct," he said. “Trump is out there on his own, leading a demagogic attack on the institutions of free democracy,“ he said. “We are into terrible authoritarian tendencies.”

Mr Bernstein spoke out against Mr Trump's behaviour after the president escalated his ongoing war on the mainstream media with a single tweet.

Mr Trump's dealings with the media have always been fraught, but his incendiary tweet followed a particularly chaotic press conference in which he called the assembled journalists "dishonest" and accused a Jewish reporter of lying before ordering him to sit down.

He also asked a black reporter asking about the Congressional Black Caucus: “Are they friends of yours? Set up a meeting.”

His use of "enemy of the American people" drew comparisons with despots like Stalin and Mao Zedong, who had a habit of using the phrase about opponents shortly before they died or “disappeared”.

It's “how dictators get started,“ Senator John McCain said the same day on NBC's show Meet the Press, of Mr Trump's comments.

Before the election, the University of Maryland's chair of broadcast journalism discerned “Nixon's echo—and, perhaps, Nixon's revenge“ in Mr Trump's rhetoric on the campaign trail.

“He, too, obsessively sought to manipulate the news coverage he desperately craved and wasn’t afraid to use intimidation if he thought it would help,” Mark Feldstein wrote in The Washington Post.

Mr Nixon's attacks on the press struck a chord with voters, helping carry him to power and encouraging more of the same, Mr Feldstein wrote.

“Nixon’s conduct in office presents a chilling example of what a President Trump could do,“ he said.

The controversial orders Donald Trump has already issued Show all 9 1 /9 The controversial orders Donald Trump has already issued The controversial orders Donald Trump has already issued Trump and the media White House Press Secretary Sean Spicer takes questions during the daily press briefing Getty Images The controversial orders Donald Trump has already issued Trump and the Trans-Pacific Partnership Union leaders applaud US President Donald Trump for signing an executive order withdrawing the US from the Trans-Pacific Partnership negotiations during a meeting in the Roosevelt Room of the White House in Washington DC. Mr Trump issued a presidential memorandum in January announcing that the US would withdraw from the trade deal Getty The controversial orders Donald Trump has already issued Trump and the Mexico wall A US Border Patrol vehicle sits waiting for illegal immigrants at a fence opening near the US-Mexico border near McAllen, Texas. The number of incoming immigrants has surged ahead of the upcoming Presidential inauguration of Donald Trump, who has pledged to build a wall along the US-Mexico border. A signature campaign promise, Mr Trump outlined his intention to build a border wall on the US-Mexico border days after taking office Getty Images The controversial orders Donald Trump has already issued Trump and abortion US President Donald Trump signs an executive order as Chief of Staff Reince Priebus looks on in the Oval Office of the White House. Mr Trump reinstated a ban on American financial aide being granted to non-governmental organizations that provide abortion counseling, provide abortion referrals, or advocate for abortion access outside of the United States Getty Images The controversial orders Donald Trump has already issued Trump and the Dakota Access pipeline Opponents of the Keystone XL and Dakota Access pipelines hold a rally as they protest US President Donald Trump's executive orders advancing their construction, at Columbus Circle in New York. US President Donald Trump signed executive orders reviving the construction of two controversial oil pipelines, but said the projects would be subject to renegotiation Getty Images The controversial orders Donald Trump has already issued Trump and 'Obamacare' Nancy Pelosi who is the minority leader of the House of Representatives speaks beside House Democrats at an event to protect the Affordable Care Act in Los Angeles, California. US President Donald Trump's effort to make good on his campaign promise to repeal and replace the healthcare law failed when Republicans failed to get enough votes. Mr Trump has promised to revisit the matter Getty Images The controversial orders Donald Trump has already issued Donald Trump and 'sanctuary cities' US President Donald Trump signed an executive order in January threatening to pull funding for so-called "sanctuary cities" if they do not comply with federal immigration law AP The controversial orders Donald Trump has already issued Trump and the travel ban US President Donald Trump has attempted twice to restrict travel into the United States from several predominantly Muslim countries. The first attempt, in February, was met with swift opposition from protesters who flocked to airports around the country. That travel ban was later blocked by the Ninth Circuit Court of Appeals. The second ban was blocked by a federal judge a day before it was scheduled to be implemented in mid-March SANDY HUFFAKER/AFP/Getty Images The controversial orders Donald Trump has already issued Trump and climate change US President Donald Trump sought to dismantle several of his predecessor's actions on climate change in March. His order instructed the Environmental Protection Agency to reevaluate the Clean Power Plan, which would cap power plant emissions Shannon Stapleton/Reuters

In 1971, Mr Nixon told the chairman of the Joint Chiefs of Staff, "the press is your enemy", according to a 1971 Oval Office tape quoted in the Washington Post. “Enemies. Understand that? … Now, never act that way … give them a drink, you know, treat them nice, you just love it, you're trying to be helpful. But don't help the bastards. Ever. Because they're trying to stick the knife right in our groin.”

But unlike Mr Nixon, Mr Bernstein emphasised that Mr Trump was not speaking to one person—the tape was only made public later—but to his 25 million Twitter followers when, after weeks of news reports on scandals and chaos in his White House, he called most of the major news organisations in the United States "enemies of the American People!"