David Cameron has said conspiracy theories about Jews may be the first stepping stones to Islamist extremism.

He also warned of extremists who believe that “Jews exercise malevolent power” and engage in conspiracy theories that Mossad was behind the September 11 terror attacks in 2001.

In a major speech in Birmingham , the Prime Minister outlined a five-year plan to combat Islamists which will see the government “confront, head on, the extreme ideology” behind terrorist actions.

Mr Cameron said he had visited the King David Jewish primary school in the city on Monday morning. The majority of its students are Muslim.

A five-year plan would involve tackling violent and non-violent extremism, Mr Cameron said, using anti-Israel rhetoric as an example.

He said if people claimed “violence in London isn’t justified, but suicide bombs in Israel are a different matter”, then "you too are part of the problem".

Referring to hate speakers on university campuses, Mr Cameron drew parallels with Holocaust denier David Irving, who he said was rejected by university leaders. But a "blind eye" was often turned to Islamist extremists, he said.

Speaking about those who have been convicted in this country of planning terror attacks, Mr Cameron said: “It may begin with hearing about the so-called Jewish conspiracy and then develop into hostility to the West and fundamental liberal values, before finally becoming a cultish attachment to death.”

Mr Cameron also spoke about the failure of some ethnic minorities to integrate into British society.

“For all our successes as a multi-racial, multi-faith democracy, we have to confront a tragic truth that there are people born and raised in this country who don’t really identify with Britain and feel little or no attachment to other people here,” Mr Cameron said.

He condemned the National Union of Students for agreeing to work with Cage, the campaign group linked to Daesh terrorist Mohammed Emwazi.

"When you choose to ally yourselves with an organisation like Cage, which called Jihadi John a ‘beautiful young man’ and told people to 'support the jihad' in Iraq and Afghanistan, it really does, in my opinion, shame your organisation and your noble history of campaigning for justice,” Mr Cameron said.