London Mayor Sadiq Khan told CNBC that President Donald Trump has become a "poster boy" for the far right, in an escalating war of words between the two political figures.
Trump is on the second day of his state visit to the U.K. where is meeting with royalty, business leaders and outgoing Prime Minister Theresa May. Khan told CNBC's Tom Chitty Tuesday that around the world, far-right groups that had previously been marginalized were now being normalized and "using Donald Trump as their poster boy."
Khan had already compared Trump to the fascists of the 1930s and 40s in an opinion article published Saturday, claiming the U.S. president "gives comfort to the far right."
Just before his flight touched down in the U.K. on Monday, Trump offered a fiercely-worded response, tweeting that Khan was a "stone cold loser."
Khan said Tuesday that he was surprised by Trump's response on social media.
"It's the sort of behavior I'd expect from an 11-year-old, not from the president of the USA. It's for Donald Trump to decide how he behaves and not for me to respond in that manner."
Thousands of protesters lined London's streets Tuesday, with anger stemming from Trump's position on issues such as the treatment of women, Muslim communities and abortion rights.
Khan said people had a right to express their concerns about Trump's polices, but that it did not equate to a dislike of the U.S. in general.
"We love America, we love Americans. We revere the founding fathers and respect the presidents we've had in the past," he told CNBC.
Trump and Khan have battled before. After the terror attack at London Bridge in 2017, Trump criticized Khan's handling of the incident, while Khan's office called Trump "ill-informed."
The White House did not immediately respond to a request for comment from CNBC.