US President Donald Trump described Pakistani-origin London Mayor Sadiq Khan as "nasty" and a "stone cold loser" as he landed here on Monday with wife Melania and an entourage of his family for a three-day state visit hosted by Queen Elizabeth II.
Just moments before his Air Force One touched down at Stansted Airport, the US President took to Twitter in his characteristic style to attack London Mayor Khan with whom he has clashed in the past, terming him "nasty" and a "stone cold loser".
"Sadiq Khan who by all accounts has done a terrible job as Mayor of London, has been foolishly "nasty" to the visiting President of the United States, by far the most important ally of the United Kingdom. He is a stone cold loser who should focus on crime in London, not me," he said.
Trump compared the 48-year-old Khan with New York Mayor de Blasio as having done an equally "terrible job".
Khan recently branded Trump a fascist and divisive figure who should not be accorded the pomp and ceremony associated with a UK state visit.
Protests are planned across the UK during the visit, including in London, Manchester, Belfast and Birmingham and a giant balloon depicting Trump as a baby is to take to the skies once again over London, in a repeat of his last UK visit in 2018.
On Monday, the US President will be given a tour of Westminster Abbey and will also meet Prince Charles and the Duchess of Cornwall for tea at their Clarence House residence in London.
In the evening, the Queen will host the ceremonial state banquet at Buckingham Palace for Trump and the First Lady Melania Trump. She will be joined by the Duke and Duchess of Cambridge, William and Kate.
The agenda for Trump's weeklong tour of Europe includes the World War II D-Day commemoration ceremonies on both sides of the English Channel and his first presidential visit to Ireland, which will include a stay at his coastal golf club.
British Prime Minister May, who is to preside over bilateral talks at Downing Street, will formally resign as PM a day after the US President leaves London on Thursday.
Labour leader Jeremy Corbyn, House of Commons Speaker John Bercow, and Liberal Democrat leader Vince Cable are all boycotting the state banquet.
President Trump will be staying at the US ambassador's residence Winfield House, in central London's Regent's Park.
George W Bush and Barack Obama are the only other US presidents to be given a state visit. State visits differ from official visits and are normally at the invitation of the Queen, who acts on advice from the government.