London (CNN) Long-time Trump critic and London Mayor Sadiq Khan has called the US President "one of the most egregious examples of a growing global threat," in an explosive newspaper article published just hours before Trump's first state visit to the UK.

Writing in the Observer newspaper on Sunday, Khan said it was "un-British" to be rolling out the red carpet for a President "whose divisive behavior flies in the face of the ideals America was founded upon -- equality, liberty and religious freedom."

"In years to come, I suspect this state visit will be one we look back on with profound regret and acknowledge that we were on the wrong side of history," said the Mayor, who in the past has made no secret of his disapproval of the President.

Khan likened Trump to a number of far-right leaders -- such as Marine Le Pen in France -- who are "using the same divisive tropes of the fascists of the 20th century to garner support."

The comments came a day before Trump was due to arrive in the capital for a three-day visit, stoking an ongoing feud between the London Mayor and the US President

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