David Cameron today rejected criticism of his decision to attack multi-culturalism, saying a "whole new way of thinking" was needed.

In a controversial speech yesterday, the British Prime Minister declared multi-culturalism a failure and called for a tougher approach in tackling Islamist extremism.

Shadow justice secretary Sadiq Khan responded by accusing Mr Cameron of "writing propaganda for the EDL (English Defence League)", while Muslim groups described the Prime Minister's words as "disappointing".

But Mr Cameron stood by his philosophy, telling the Sunday Telegraph: "You have to confront the extremism itself. You have to say to the people in Birmingham Central Mosque, or wherever, who are saying 9/11 is a Jewish conspiracy, that that is not an acceptable attitude to have.

"We don't tolerate racism in our society carried out by white people, we shouldn't tolerate extremism carried out by other people.

"It certainly means changing the practice, changing the groups you fund, the people you engage, the platforms you share with people, the people you let into the country. I think it needs a whole new way of thinking."

Speaking at a security conference in Germany with fellow world leaders, Mr Cameron said: "Frankly, we need a lot less of the passive tolerance of recent years and much more active, muscular liberalism.

"A passively tolerant society says to its citizens: as long as you obey the law, we will leave you alone. It stands neutral between different values.

"A genuinely liberal country does much more. It believes in certain values and actively promotes them - freedom of speech, freedom of worship, democracy, the rule of law, equal rights regardless of race, sex or sexuality.

"It says to its citizens: this is what defines us as a society, to belong here is to believe in these things.

"Each of us in our own countries must be unambiguous and hard-nosed about this defence of our liberty."

He said British society had been too cautious in standing up to "unacceptable views and practices" when they involve people who are not white and cited forced marriage as an example.

He continued: "Under the doctrine of state multi-culturalism, we have encouraged different cultures to live separate lives, apart from each other and the mainstream."

Mr Cameron said there was a clear distinction between the religion of Islam and the political ideology of Islamist extremism.

But he said there were organisations that, without being violent, were nevertheless "part of the problem", adding: "Some organisations that seek to present themselves as a gateway to the Muslim community are showered with public money despite doing little to combat extremism."

He said such groups had to be denied public money and the opportunity to share platforms with ministers.

Mr Cameron's comments came as the anti-Muslim EDL held a major demonstration in Luton, prompting accusations that he was playing into the hands of the far-right.

EDL leader Stephen Lennon reportedly said of Mr Cameron: "He's now saying what we're saying. He knows his base."

Conservative co-chairman Baroness Warsi sought to turn the tables on Labour by demanding an apology from shadow justice secretary Sadiq Khan after he accused Mr Cameron of "writing propaganda for the EDL".

But a spokeswoman for Mr Khan accused Lady Warsi of trying to create an "artificial row" to distract from the Government's embarrassment about the timing of the speech.

Mohammed Shafiq, chief executive of Muslim youth group the Ramadhan Foundation, accused Mr Cameron of trying to "score cheap political points" in a way that would "rip communities apart".

"Singling out Muslims as he has done feeds the hysteria and paranoia about Islam and Muslims," he said.

"Multi-culturalism is about understanding each others' faiths and cultures whilst being proud of our British citizenship - it would help if politicians stopped pandering to the agenda of the BNP and the fascist EDL."

Dr Faisal Hanjra, assistant secretary general of the Muslim Council of Britain, described Mr Cameron's speech as "disappointing".

"Again, it seems very much that the Muslim community is in the spotlight and being treated as part of the problem rather than part of the solution."

Foreign Secretary William Hague rejected suggestions that Mr Cameron's speech was ill-timed.

"This is a Prime Minister giving a speech about the future of our country - that doesn't have to be rescheduled because some people have chosen to walk down a street that particular day," he told BBC1's Andrew Marr Show.

"This is a speech that will endure over the months and years, long after people have forgotten what was going on on that particular Saturday afternoon."

Trevor Phillips, chair of the Equalities and Human Rights Commission, refused to criticise the Prime Minister's claim multiculturalism had failed.

He admitted Mr Cameron "may have made life a bit more difficult for himself" by combining the issues of terrorism and integration in one speech but added the Prime Minister was right to say it was not the role of Government to tell people to embrace multiculturalism.

Mr Phillips told the BBC's Andrew Marr Show: "People don't choose not to integrate mostly. There are a few people on the edges who don't want to integrate with anybody else but most people, if they don't mix, it's because they don't have the choice.

"There are two things which make that happen. One, is discrimination. So if you're going to back this up, we have to have a really renewed and tough battle against discrimination.

"And the second will be the effect of economic policy. Cuts may end up isolating communities and the two million jobs the Government says it wants to create, if those jobs are not equally accessible to people from Pakistani communities, from black communities, indeed from disabled people and women, then actually that is what will fracture our society."

He added: "The key thing here is that if you take the biggest Muslim community, Pakistanis, 25% of Pakistani men are taxi drivers, 75% of Pakistani and Bangladeshi women are economically inactive. That is the issue.

"The issue here is not some sort of abstract culture. The place most people integrate is in the workplace. If people can't get jobs, you can't expect them to integrate."