Boris Johnson has urged Londoners to vote for Conservative candidate Zac Goldsmith in the London Mayoral elections, saying there is an “antisemitic sickness” within Jeremy Corbyn’s Labour Party.

In his column in the Telegraph, the London Mayor said there was a “new boldness in the use of virulent anti-Israel and anti-Jewish language” that had led to Jewish Labour MPs being bullied in their own constituencies, and antisemitism being expressed on campuses and on social media.

The reason, he said, was because “the Corbynistas believe in the most extreme ideology that Labour has ever espoused”.

Mr Johnson continued his piece by expressing his fears that, if Sadiq Khan won the London mayoralty, these Corbynistas would “plant the red flag back on the top of City Hall”. The only way to stop them, he said, was by voting for Mr Goldsmith.

Of the Labour candidate, Mr Johnson wrote: “Sadiq Khan has himself belatedly admitted that Labour is afflicted with antisemitism. He has rightly called it a ‘badge of shame’.”

He said Mr Khan had himself shared platforms with speakers who had controversial views.

Mr Johnson concluded: “I don’t want him running our capital. Zac Goldsmith is a man of principle, a passionate campaigner, a One Nation Tory who has served his Richmond constituency so well that he recorded the biggest increase in his majority in 2015. He must win.”