The Prime Minister has issued a stark warning against Muslim communities that "quietly condone" Islamic extremism and has called on them to face up to their own responsibilities rather than point the finger at others.

David Cameron, speaking at the Globsec security conference in Slovakia after recent extremist behaviour such as the death in Iraq of British suicide bomber Talha Asmal and the flight to Syria of three sisters and their children, called on internet service providers to take stronger action to counter Islamic extremism peddled online. He urged Muslim communities to take more active steps to counter the "poisonous ideology" of Islamic State that the West is evil, democracy wrong and that women are innately inferior.

The Prime Minister said individuals and communities must take a stronger stand against such extremism rather than blaming the state if young Muslims are not to continue to be enticed to join jihad in Syria.

He said: "Too often we hear the argument that radicalisation is the fault of someone else. That blame game is wrong – and it is dangerous. By accepting the finger-pointing – whether it's at agencies or authorities – we are ignoring the fact that the radicalisation starts with the individual."

Some Muslims buy into aspects of the critique of the West without going so far as to advocate violence, he admitted. But even this gives the Islamic narrative weight because it leads to acceptance of these anti-Western prejudices.

"This paves the way for young people to turn simmering prejudice into murderous intent, to go from listening to firebrand preachers online to boarding a plane to Istanbul and travelling onward to join the jihadis."

He continued: "We've always had angry young men and women buying into supposedly revolutionary causes. This one is evil, is it contradictory, it is futile – but it is particularly potent today. I think part of the reason it's so potent is that it has been given this credence.

"So if you're a troubled boy who is angry at the world or a girl looking for an identity, for something to believe in and there's something that is quietly condoned online or perhaps even in parts of your local community, then it's less of a leap to go from a British teenager to an Isil fighter or an Isil wife than it would be for someone who hasn't been exposed to these things."

These jihadists often had surprisingly comfortable backgrounds.

"These are young people, boys and girls, leaving often loving, well-to-do homes, good schools and bright prospects travelling thousands of miles from home to strap explosives to their chests and blow themselves up and kill innocent people, to live in a place where marriage is legal at nine and where women's role is to serve the jihadists, to be part of a so-called state whose fanatics are plotting and encouraging acts of despicable terrorism in the countries from which they have come," the Prime Minister said.

"It is an Islamist extremist ideology one that says the west is bad and democracy is wrong that women are inferior and homosexuality is evil. It says religious doctrine trumps the rule of law and caliphate trumps nation state and it justifies violence in asserting itself and achieving its aims. The question is: how do people arrive at this worldview?"

His speech came at the start of the Muslim season of fasting, the month of Ramadan.

He spoke out after Manzoor Moghal, chairman of the Muslim Forum, described a climate of division in some British towns where foreign policy, Islamophobia and online propaganda are being used as scapegoats.

Dr Shuja Shafi, secretary general of the Muslim Council of Britain, said today: "The Prime Minister is absolutely right in saying that finger-pointing when it comes to radicalisation is wrong and dangerous. Yet the media response to the Prime Minister's speech suggests that the finger is firmly pointing only at Muslim communities, even though Muslims and Muslim organisations around the country have loudly and unequivocally condemned terrorism, they continue to be demonised.

"Terrorism blights all our lives, not least amongst Muslim families. None of us can help but feel the pain of those parents whose children and loved-ones have suddenly uprooted themselves and joined the cult that is Daesh, or ISIL. The Muslim Council of Britain has initiated a process to explore community led responses to tackle terrorism. This process involves not just Muslims themselves, but also friends and partners in wider society.

"We are in no doubt that there are many shortcomings in Muslim civil society, which like wider society, is struggling to challenge the terrorist narrative that is potent outside the mosque and in the margins of the internet. But to suggest that Muslim communities have led young people to extremism or gives credence to extremist ideology is erroneous, wrong and counter productive.

"It has been suggested that Muslims are not doing enough and somehow condone extremism. We would argue that clear evidence should be presented and wrongdoing challenged, rather than perpetuate insinuation persistently.

"The reasons why people are drawn to this are many and complex. Simplifying the causes for tabloid consumption helps no one but the extremists. Blaming only Muslims for terrorism is just as bad as placing responsibility only at the door of government and its agencies. There must be a better way, one where Muslim communities, wider British society and the government work together with, not against each other to tackle the problem."