The former head of US intelligence James Clapper has said the scandals engulfing President Donald Trump are worse than the infamous Watergate case.

Mr Clapper this morning reflected on living through the major political scandal in the 1970s that rocked President Richard Nixon’s administration.

"I lived through Watergate. I was on active duty then in Air Force, I was a young officer. It was a scary time,” he told the National Press Club in Canberra.

David frost is remembered as the man who interviewed Richard Nixon when he apologised for Watergate. (AAP) (AAP)

“It was against the backdrop of the post-Vietnam trauma as well which seemed, at least in my memory, amplified as a backdrop, am amplified the crisis in our system with Watergate.

“I have to say, though, I think you compare the two that Watergate pales really in my view compared to what we're confronting now.”

Mr Clapper said he was "concerned" about Mr Trump's assault on US institutions.

He also reiterated his concern about Mr Trump's "assault" on the United States and its institutions.

"I am very concerned about the assault on our institutions coming from both an external source - read Russia - and an internal source, the president himself.

"Russia embarked on a campaign to interfere with our presidential election which was unprecedented in its directness and aggressiveness."