The prime minister will criticise "state multiculturalism" in his first speech on radicalisation and the causes of terrorism since being elected.
Addressing a security conference in Germany, David Cameron will argue the UK needs a stronger national identity to prevent people turning to extremism.
Mr Cameron will draw a clear distinction between Islam the religion and what he describes as "Islamist extremism" - a political ideology he says attracts people who feel "rootless" within their own countries."We need to be clear: Islamist extremism and Islam are not the same thing."
The government is currently reviewing its policy to prevent violent extremism, known as Prevent, which is a key part of its wider counter-terrorism strategy.
He will say that under the "doctrine of state multiculturalism", different cultures have been encouraged to live separate lives.
Building a stronger sense of national and local identity holds "the key to achieving true cohesion" by allowing people to say "I am a Muslim, I am a Hindu, I am a Christian, but I am a Londoner... too", he will say.
