Sadiq Khan said President Donald Trump's visit to the UK should be cancelled after the "cruel and shameful" travel ban introduced by the new leader.
The Mayor of London appeared on Peston on Sunday and said the special relationship between the UK and America is a good one, but should have meant Trump was "called out when he was wrong".
Speaking of the executive order banning travel to the US for people from seven predominantly Muslim countries, Mr Khan said: "I think this ban on people from Muslim majority countries and ending the refugee programme is cruel and shameful."
The Mayor continued: "In those circumstances, we should not be rolling out the red carpet."
It comes as MPs in Parliament vote on the President's visit to the UK today (February 20), despite a petition of more than 1.6milliion people arguing for the state visit to be cancelled .
He said: "Donald Trump should be invited to make an official State Visit because he is the leader of a free world and U.K. is a country that supports free speech and does not believe that people that appose our point of view should be gagged."
Prime Minister Theresa May, however, previously said the state visit will not be cancelled.
Should Trump visit, the main meeting has snubbed London, and is due to be held in Birmingham instead.
Another protest will be held in London today (Monday February 20) against the proposition in Westminster.
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