Labour’s London mayor candidate Sadiq Khan has described his experience of meeting extremists who claim the September 11 terror attacks were a “Mossad conspiracy”.

Mr Khan said he had come across people who believed Jewish workers in New York had been “tipped off” to stay away from the Twin Towers before the planes hit the buildings.

Speaking at a parliamentary lunch on Thursday, the former Communities Minister said he had “lost count” of the instances when he had to challenge “hideous views”.

He also spoke more broadly about Islamic extremism and the steps he would take to tackle it if elected to City Hall next May.

Mr Khan said: “Extremism isn't a theoretical risk. Most British Muslims have come across someone with extremist views at some point - and so have I. It's affected my personal life, my friendships, and my career.

“People I knew as a boy have gone on to hold extremist views, and even to act on them in terrible ways. When I was a lawyer, as well as representing people who were badly treated by the police or their employers, I sometimes had the unpleasant job of representing people with extremist views.

“It was horrible - but it went with the job. I’ve lost count of the number of times I’ve had to challenge the hideous views of seemingly intelligent and articulate people.

“People who look and sound like normal Londoners, until they say that 9/11 was a Mossad conspiracy. That the Jewish workers in the twin towers were tipped off and escaped.

“That Western foreign policy is the cause of all the world’s problems. That there could be a land of milk and honey, if there was an Islamic caliphate. I could go on.”

Mr Khan said that if elected as mayor he would work to bring together schools and charities encourage young Londoners to mix regardless of race, faith or background.

In September the Tooting MP told the JC how he had began his Ramadan fast at synagogues three times last summer and had discussed with rabbis the best ways to make London a beacon for interfaith initiatives.