Donald Trump ranted about how "fake news" is being broadcast on UK television channels - just hours after arriving on British soil.
The US President, 72, moaned on Twitter about CNN and its owner AT&T and again called on people to stop watching the coverage.
He argued CNN portrays "a false picture" of the US.
"Just arrived in the United Kingdom. The only problem is that @CNN is the primary source of news available from the U.S. After watching it for a short while, I turned it off. All negative & so much Fake News, very bad for U.S. Big ratings drop. Why doesn’t owner @ATT do something," Mr Trump wrote.
And just 13 minutes later, the politician continued his grumble in a second tweet which featured a clumsy spelling error.
He added: "I believe that if people stoped [sic] using or subscribing to @ATT, they would be forced to make big changes at @CNN, which is dying in the ratings anyway. It is so unfair with such bad, Fake News! Why wouldn’t they act. When the World watches @CNN, it gets a false picture of USA. Sad!"
Each tweet has been shared thousands of times but many have reacted in fury.
"Focus. Focus on your big London trip," wrote one person.
"We love CNN here," another Brit wrote.
"You should try Cbeebies. It's great for calming down angry overtired babies," another person joked.
Others simply pointed out the politician's spelling gaffe.
Even before landing at Stansted Airport, Mr Trump blasted Sadiq Khan on Twitter .
In a vicious attack, Mr Trump called the London Mayor "nasty" and a "stone cold loser."
But Sadiq Khan's spokesman hit back, saying "childish insults" should be "beneath the president of the United States".
The statement said: “This is much more serious than childish insults which should be beneath the President of the United States.
"Sadiq is representing the progressive values of London and our country warning that Donald Trump is the most egregious example of a growing far-right threat around the globe, which is putting at risk the basic values that have defined our liberal democracies for more than 70 years.”
