The pair's long-running rivalry was reignited after the London Mayor accused Mr Trump of dealing with the major hurricane bearing down on the US by spending the day “on the golf course”.

The controversial commander-in-chief spent part of Monday playing a round of golf at his Trump National Golf Club in Virginia while millions of Americans braced themselves for the Category 4 Hurricane Dorian, which has already claimed lives in the Bahamas.

Speaking to Politico, Mr Khan said the President "is a guy who amplifies racist tweets; amplifies the tweets of fascists; says things that are deeply objectionable." 

He added: "If I don't stand up and call that out I think I'm doing a disservice to Londonders who chose me as their mayor."

But the comments provoked a predictable backlash from the President who accused Mr Khan of being "incompetent" while spelling both his first and last names incorrectly.

"The incompetent Mayor of London, Sadique Kahn (sic), was bothered that I played a very fast round of golf yesterday," he tweeted.

"Many Pols exercise for hours, or travel for weeks. Me, I run through one of my courses (very inexpensive). President Obama would fly to Hawaii.

"Kahn should focus on 'knife crime,' which is totally out of control in London. People are afraid to even walk the streets. He is a terrible mayor who should stay out of our business!"

The pair's last clash came after Mr Trump described the Labour politician as a "stone cold loser" for criticising Theresa May's decision to offer the US leader a state visit to the UK.