Ahead of President Donald Trump’s state visit to the U.K. that begins Monday, London’s mayor and vocal Trump critic Sadiq Khan excoriated the U.S. leader in a Saturday op-ed — likening him to the “fascists of the 20th century” and saying it was “un-British” to give him the red carpet treatment.

Writing in The Observer, Khan lambasted Trump for exploiting “xenophobia, racism and ‘otherness’ as an electoral tactic,” and for “lying deliberately and repeatedly to the public.”

Describing the president as “one of the most egregious examples of a growing global threat” of far-right politics, Khan accused Trump — as well as Hungary’s Viktor Orbán, France’s Marine Le Pen and Britain’s Nigel Farage — of not just “using the same divisive tropes of the fascists of the 20th century to garner support,” but also employing “new sinister methods to deliver their message.”