London mayoral candidate Sadiq Khan has said Muslims have to lead the fight in tackling extremism as he said people he grew up with went on to "act" on their hardline views.
The Labour MP, who railed against "social segregation" in a Westminster speech, also revealed his fears that his teenage daughters could be exploited by Islamist fanatics and drawn to IS.
Mr Khan said "too many" Muslims grow up not knowing anyone from a different background, and the same applies to British people that have "never befriended a Muslim".
In a powerful address to journalists in the Parliamentary Lobby days after the Paris attacks, the Tooting MP also launched a thinly-veiled attack on Labour leader Jeremy Corbyn, saying he would have no hesitation in ordering "shoot to kill" amid Paris-style attacks as he lives "in the real world".
The 45-year-old, who will face Tory candidate Zac Goldsmith after winning the Labour nomination to stand in September, spoke of his own experiences of being confronted with radicals, saying it affected "my personal life, my friendships, and my career".
He said: “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 kalifate. I could go on."
Key extract from Sadiq Khan speech to Lobby on tackling "social segregation" and, in turn, extremism pic.twitter.com/Y3OE4ZWyjI— Graeme Demianyk (@GraemeDemianyk) November 19, 2015
Calling extremism the "cancer eating at the heart of our society", he 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."
The father of two daughters went on to say the "fight is personal for me". "Like all parents, I want to know that my daughters are safe," he said. "I worry that they or their friends could be groomed by extremists on the internet. Or tricked into running off to Syria like other children have been."
He said not enough has been done to "root out" radicalisation in Britain, and "in this week of all weeks that makes me angry" - and hit out at successive Governments that have "tolerated segregation in British society".
"In doing so, we've allowed the conditions that permit extremism to continue unchecked," he said.
"We’ve protected people’s right to live their cultural life at the expense of creating a common life.
"Too many British Muslims grow up without really knowing anyone from a different background. Without understanding or empathising with the lives and beliefs of others.
“And too many British people have never befriended a Muslim. Never worked together, never eaten together, never played sports together. As a result, too many people have formed a single identity - too often based around their religion or ethnicity.
“This creates the conditions for extremism and radicalisation to take hold. Social segregation will not go away on its own. Tackling it will take a prolonged and concerted effort by us all."
Lovely Sadiq Khan joke involving Sajid Javid to Lobby: "You wait ages for a son of an immigrant bus driver and two turn up at once."— Graeme Demianyk (@GraemeDemianyk) November 19, 2015
Mr Khan said he believed the country was safer as the result of the US drone strike - in a joint operation with the UK - which killed Mohammed Emwazi in Syria earlier this month.
He also voiced his strong support for armed police officers who had to take "split second decisions" on when to open fire, saying: "I live in the real world."