London Mayor Sadiq Khan on Tuesday slammed President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE, calling him a “poster boy for the far-right movement around the world” as thousands gathered in London to protest Trump’s state visit.

Khan in an interview with Sky News criticized Trump for his immigration policies, citing the Muslim travel ban and "zero tolerance" family separation policy at the U.S.-Mexico border.

“Surely we should be saying ‘listen, you know, you do realize you’re a poster boy for the far-right movement around the world,’ ” Khan said.

ADVERTISEMENT

London Mayor @SadiqKhan says @realDonaldTrump is "a poster boy for the far-right movement around the world", and that @theresa_may should tell him his values are 'not reflected' by the UK.



For the latest on Donald #Trump's state visit, head here: https://t.co/mAPnOdt259 pic.twitter.com/RAPDsg67O5 — Sky News (@SkyNews) June 4, 2019

Trump and Khan have often exchanged barbs since Trump took office in 2017.

Khan wrote a fiery op-ed on Saturday ahead of Trump's visit to the United Kingdom, saying his own country was on the “wrong side of history” for allowing the state visit.

“History teaches us of the danger of being afraid to speak truth to power and the risk of failing to defend our values from the rise of the far right. At this challenging time in global politics, it’s more important than ever that we remember that lesson,” he wrote.

Trump fired back early Monday by calling Khan a “stone cold loser.”

The mayor’s office criticized Trump’s “childish insults,” saying his antics should be beneath the office of the president.

“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,” Khan's office added.

Trump on Tuesday arrived at Downing Street for talks with outgoing Prime Minister Theresa May Theresa Mary MayAre US-Japan relations on the rocks? Trump insulted UK's May, called Germany's Merkel 'stupid' in calls: report Bolton says Boris Johnson is 'playing Trump like a fiddle' MORE.

Sky News reported that around 10,000 anti-Trump protesters have taken to the streets of London.