Trump's critique comes in response to Sadiq Khan comparing the US president to 20th-century fascists, ONA reports citing Sputnik.
Donald Trump, who is in the UK on a full state visit, has lashed out at London Mayor Sadiq Khan, who earlier called the president's trip to the country a regrettable event.
"Sadiq Khan, who by all accounts has done a terrible job as Mayor of London, has been foolishly "nasty" to the visiting President of the United States, by far the most important ally of the United Kingdom," Trump tweeted on Monday as he was arriving in the United Kingdom.
"He is a stone-cold loser who should focus on crime in London, not me," Trump continued, "Kahn [sic] reminds me very much of our very dumb and incompetent Mayor of NYC, de Blasio, who has also done a terrible job − only half his height. In any event, I look forward to being a great friend to the United Kingdom, and am looking very much forward to my visit."