President Donald Trump on Saturday fired off another volley in his escalating feud with the US media, aiming a Twitter tirade at CNN, NBC and a morning show host he taunted as ‘dumb as a rock.’

The outburst came at the end of a week during which the US leader railed against major news organizations as ‘fake news,’ before launching a crude personal attack on Mika Brzezinski and Joe Scarborough, who headline the ‘Morning Joe’ program on the left-leaning MSNBC cable network.

‘Crazy Joe Scarborough and dumb as a rock Mika are not bad people, but their low rated show is dominated by their NBC bosses. Too bad!’ he wrote, seemingly trying to get in the final word in his clash with the journalists.

Apparently stung by critical coverage on the show, Trump on Thursday had tweeted: ‘I heard poorly rated @Morning_Joe speaks badly of me (don't watch anymore).

‘Then how come low I.Q. Crazy Mika, along with Psycho Joe came to Mar-a-Lago 3 nights in a row around New Year's Eve, and insisted on joining me. She was bleeding badly from a face-lift. I said no!’

The comments sparked a major backlash, as well as condemnation from within Trump's own Republican party.

The TV hosts responded on Friday with an opinion piece in the Washington Post titled ‘Donald Trump is not well,’ questioning his ‘unmoored behavior’ and fitness to serve.

Trump on Saturday also targeted CNN, a frequent punching bag for the president.

‘I am extremely pleased to see that @CNN has finally been exposed as #FakeNews and garbage journalism. It's about time!’ he tweeted, referring to an article that the cable news channel retracted, which claimed Congress was investigating links between Trump's administration and a Russian investment fund.

Three CNN journalists resigned over the article, which was posted on the network's website on June 22 before being yanked the next day.

He also suggested in a third tweet that veteran ex-Fox journalist Greta Van Susteren, who left MSNBC this week, ‘was let go by her out of control bosses at @NBC & @Comcast because she refused to go along w/ 'Trump hate!'‘

Trump's spokeswoman Sarah Huckabee Sanders said earlier this week that his attacks on Brzezinski, Scarborough and other media was part of his natural instinct to ‘fight fire with fire.’