David Cameron has served notice on TV channels and internet firms to do much more to help combat Islamist extremists.
The Prime Minister hit out at online giants like Google, Facebook and YouTube for claiming it was too difficult for them to aid the security services in monitoring potential terrorists and curbing 'hate' videos.
He also urged broadcasters to stop giving airtime to extremists who were unrepresentative of mainstream Muslim opinion and who fomented radicalisation that could lead to fresh recruits for so-called Islamic State.
In a wide-ranging speech, Mr Cameron also set out new plans to allow parents to cancel the passports of children they fear are being radicalised by Islamists.
Other key new proposals include fresh protections against forced marriage and moves to end segregation in schools and housing estates.
Speaking in Birmingham, Mr Cameron told internet giants that "I just don't buy it" that it was too difficult to track detailed messages being sent out by Islamist extremists to brainwash impressionable youngsters.
Security services have repeatedly warned of the online power and reach of Islamist videos and Mr Cameron signalled he would ram through a new data communications bill to help security services better monitor threats.
"We need our internet companies to go further in helping us identify potential terrorists online. Many of their commercial models are built around monitoring platforms for personal data, packaging it up and selling it on to third parties," he said.
"And when it comes to doing what's right for their business, they are happy to engineer technologies to track our likes and dislikes. But when it comes to doing what's right in the fight against terrorism, we too often hear that it's all too difficult.
"I'm sorry, I just don't buy it. They have shown with the vital work they are doing in clamping down on child abuse images that they can step up when there is a moral imperative to act. And its now time for them to do the same to protect their users from the scourge of radicalisation."
The Prime Minister pointed out that British youngsters were "watching videos that eulogise ISIL as a pioneering state taking on the world, that makes celebrities of violent murderers"
"So people today don't just have a cause in Islamist extremism in ISIL, they now have its living and breathing expression," he said.
But some critics have already expressed concerns about freedom of speech and worries over the definition of 'extremist' due in any legislation.
Referring to TV and radio stations, Mr Cameron said that "there are so many strong, positive Muslim voices being drowned out" by the extremists and said he wanted "to issue a challenge to the broadcasters in our country".
"You are free to put whoever you want on the airwaves. But there are a huge number of Muslims in our country who have a proper claim to represent liberal values in local communities, people who run credible charities and community organisations, councillors and MPs, so do consider giving them the platform they deserve.
"I know other voices may make for more explosive TV.. but do exercise your judgement..and do recognise the huge power you have in shaping these debates in a positive way."
Government sources refused to single out individual extremists but it is understood that radicals like Anjem Choudhary, who has been particularly outspoken, is among those in ministers' minds.
The Prime Minister, who came under fire this year for telling the BBC how to refer to so-called Islamic State, stopped short of reviving a broadcasting ban like that that gagged Gerry Adams in the 1980s.
However, Mr Cameron appeared to imply that he had backed off an earlier plan for pre-broadcast censorship of UK broadcasters giving airtime to Islamists.
He said that regulator Ofcom would have its rules reviewed to prevent foreign broadcasters screening in the UK any extreme material.
Earlier today Mr Choudhary, who is often cited on broadcasters for his extreme views, tweeted his own opposition to the new strategy.
It's nonsense that Muslims go to the Islamic State because they're extremists; they want to turn their back to the decadence of man made law— Anjem Choudary (@anjemchoudary) July 20, 2015
But others instantly backed the Prime Minister's stance.
If Cameron's speech leads to Anjem Choudhary getting less airtime, that will certainly get most British Muslims cheering— Sunny Hundal (@sunny_hundal) July 20, 2015
That was quite a speech from David Cameron. Lots of breadth and nuance - but suspect it won't convince his detractors.— Shiraz Maher (@ShirazMaher) July 20, 2015
The plan, which will be introduced immediately without a change in the law, was among a raft of measures unveiled by Mr Cameron under a five-year counter-extremism programme headed by troubled families czar Louise Casey.
The Prime Minister prefaced his remarks on his new 'cohesive communities programme' by saying that the UK was a beacon across the world for its "successful multi-racial, multi-faith democracy".
But he warned that more needed to be done to support Muslims who wanted to combat radicalisation and counter extremism in their communities.
"I know how worried some people are that their children might turn to this ideology" and even seek to travel to Syria or Iraq, he said.
"So I can announce today we are going to introduce a new scheme to enable parents to apply directly to get their child's passport cancelled to prevent travel."
No.10 sources told The Huffington Post UK that the Home Office has studied the measure, which will only affect under 16s, and concluded it could be introduced swiftly without legislation.
In a robust speech, Mr Cameron said that while it was important to stress that Islamism was not the same as 'true Islam', it was also "dangerous" to deny any link at all.
"Simply denying any connection between the religion of Islam and the extremists doesn't work because these extremists are self-identifying as Muslims," he said.
"The fact is from Woolwich to Tunisia, from Ottawa to Bali, these murderers all spout the same twisted narrative, one that claims to be based on a particular faith.
"It is an exercise in futility to deny that. More than that, it can be dangerous. To deny it has anything to do with Islam means you disempower the critical reforming voices."
Mr Cameron also unveiled plans to end the racial and religious segregation of several towns, many of them in the north.
"Areas of cities and towns like Bradford and Oldham continue to be some of the most segregated parts of our country," he said.
"It's no coincidence that these are some of the places where community relations have historically been most tense, where poisonous far right and Islamist extremists desperately try to stoke tension and foster division.
"Let me be clear. I'm not talking about uprooting people from their homes or schools and forcing integration. But I am talking about taking a fresh look at the sort of shared future we want for our young people."
Ms Casey, who impressed the Prime Minister with her work on troubled families, will report back on her review by early next year, Government sources said.
The decision to hand her the new project was welcomed by some in Labour.
Louise Casey is exactly the right person to lead the work on inclusion and extremism. No-nonsense.— Paul Richards (@Labourpaul) July 20, 2015
One key policy challenge is in areas where schools and housing now comprise 90% ethnic minorities, a problem that has dogged politicians ever since the riots of 2001.
In his speech, Mr Cameron said that estates in some areas had seen "segregation has actually increased or stayed deeply entrenched for decades".
"Government needs to start asking searching questions about social housing to promote integration and avoid segregated social housing estates where people living there are from the same single minority ethnic background.
"Similarly in education, while overall segregation in schooling is declining, in our most divided communities, the education that our young people receive is actually even more segregated than the neighbourhoods they live in."
Mr Cameron said that "bussing children to different areas is not the right approach for this country"and that he didn't want to "dismantle" faith schools.
"But it is right to look again more broadly at how we can move away from segregated schooling in our most divided communities."
All new faith academies and free schools must allocate half their places without reference to faith, he pointed out.
"But now we'll go further to incentivise schools in our most divided areas to provide a shared future for our children., whether by sharing the same site and facilities, by more integrated teaching across sites or by supporting the creation of new integrated free schools in the most segregated areas."
The Prime Minister said "there is a danger in some of our communities that you can go your whole life and have little to do with people from other faiths and backgrounds"
"So when groups like ISIL seek to rally our young people to their poisonous cause, it can offer them a sense of belonging that they can lack here at home."
The Prime Minister said that he would set up a new community engagement forum to hear directly from those challenging extremism, with practical help, protection and funding for moderate Islamic groups, as well as the UK's Syrian, Iraqi and Kurdish communities.
Under the new Extremism Bill there will be "new narrowly targeted powers to enable us to deal with these facilitators and cult leaders, and stop them peddling their hatred"
Ofcom's role will be strengthened to allow action against foreign channels that broadcast hate preachers and extremist content.
Mr Cameron also rounded on university leaders - and the National Union of Students - for failing to combat Islamist extremists with the same vigoour they use to tackle far-right speakers on campus.
"Too often university leaders look the other way through a mixture of misguided liberalism and cultural sensitivity."
"And while I am it, I want to say something to the National Union of Students," he said.
"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."
One other key announcement was consultation on legislation for lifetime anonymity for victims of forced marriage "so that no-one should ever again feel afraid to come forward and report these horrific crimes".