People entering Britain must be prepared to be tolerant or not become part of society, Tony Blair has said
In a speech at Downing Street, the prime minister said that tolerance was "what makes Britain" and warned "we must be ready to defend this attitude".
The threat came not from "generalised extremism" but "a new and virulent form of ideology associated with a minority of our Muslim community".
The Muslim Association of Britain said Mr Blair's speech was "alarming".
A spokesman said the prime minister should be "investing in our society" to help the deprived, rather than investing "millions and billions in illegal occupations" which had "not helped to promote multiculturalism in this country".
"Rather than standing up and lecturing us, it's time he puts his money where his mouth is," the spokesman said.
Mr Blair also used the speech to announce a crackdown on funding for religious and racial groups, saying in the future they would have to prove they aimed to promote community integration.
Conservative community cohesion spokesman Dominic Grieve said the speech was a "remarkable turnaround".
"Many of the problems in relation to the issues he addresses are at least in part the consequence of a philosophy of divisive multiculturalism and political correctness that has been actively promoted by the Labour Party over many years at both national and local government levels."
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