London Mayor Sadiq Khan on Saturday compared United States President Donald Trump’s actions to that of “the fascists of the 20th century” and said the United Kingdom rolling out the red carpet for Trump during his state visit is “so un-British”.

In an article in The Observer, Khan said: “President Donald Trump is just one of the most egregious examples of a growing global threat. The far right is on the rise around the world, threatening our hard-won rights and freedoms and the values that have defined our liberal, democratic societies for more than 70 years.”

“Viktor Orbán in Hungary, Matteo Salvini in Italy, Marine Le Pen in France and Nigel Farage here in the UK are using the same divisive tropes of the fascists of the 20th century to garner support, but are using new sinister methods to deliver their message,” Khan wrote. “And they are gaining ground and winning power and influence in places that would have been unthinkable just a few years ago.”

Khan, who has opposed Trump since he became a mayor in 2016, wrote: “This is a man who tried to exploit Londoners’ fears following a horrific terrorist attack [2017 London Bridge attack] on our city, amplified the tweets of a British far-right racist group, denounced as fake news robust scientific evidence warning of the dangers of climate change, and is now trying to interfere shamelessly in the Conservative party leadership race by backing Boris Johnson because he believes it would enable him to gain an ally in Number 10 for his divisive agenda.”

Khan criticised the red-carpet treatment being accorded to Trump who, with his wife Melania Trump, will be a guest of Queen Elizabeth during their three-day stay. He added: “That’s why it’s so un-British to be rolling out the red carpet this week for a formal state visit for a president whose divisive behaviour flies in the face of the ideals America was founded upon – equality, liberty and religious freedom.”

He said instead of bestowing Trump with a grand platform of acceptability to the world, people should speak out and condemn the behaviour that is “unacceptable”.

He ended the article with a word of caution: “But it’s not too late for the prime minister to do the right thing. Theresa May should issue a powerful rejection – not of the US as a country or the office of the presidency, but of Trump and the far-right agenda he embodies.”

In May 2016, Trump had challenged Khan to an IQ test after the Mayor said the President’s views on Islam were “ignorant”. After the terrorist attack on London Bridge and Borough market in 2017, he had accused Khan of “pathetic” behaviour.

Last July, Trump had again criticised Khan and said he had “done a very bad job on terrorism”.