In a tense interview on BBC One's Daily Politics, Goldsmith was pressed on why he repeatedly linked Khan to extremism without any evidence.

He said: "When Jeremy Corbyn was standing for leadership, he was attacked by people like Yvette Cooper for having given legitimacy to people with extremist views, having shared platforms. And her view at the time was that you do not do that, these people should not have any association at all with the Labour party.

"That same question has been asked of Sadiq Khan whose links to extremists – I'm not saying he's extremist..."

He added: "There are many, many examples of Sadiq Khan having shared platforms with, having given oxygen to, having made apologies for, people who have extreme views.

"That is a legitimate question to ask, the idea that someone standing for mayor of London with a big security remit should expect those questions not to be asked... is completely wrong."