A sweeping package of counter-terror measures has been unveiled by the Government as it moves to bolster the UK's defences amid warnings of a growing extremist threat that is set to last for several years.
Addressing the Royal United Services Institute (Rusi) in London, Home Secretary Theresa May said the threat from jihadists and other fanatics is "greater than it has ever been" as she revealed the range of draconian powers included in a new Counter-terrorism and Security Bill.
Within the new bill, which will be introduced to Parliament on Wednesday and should pass into law before the general election, is a legal requirement by schools, prisons and councils to put in place policies or programmes to stop would-be extremists from being drawn into terrorism.
Legislation will be clarified to make sure insurance companies can no longer foot the bill for terrorist ransoms, suspected foreign fighters will be blocked from returning to the UK and powers will be re-introduced to relocate terror suspects across the country.
The Home Secretary revealed the full extent of the anti-extremist proposals as police officers launched a counter-terrorism awareness week, which will see more than 6,000 people receive briefings at 80 venues across the country, including schools, universities, airports, shopping centres, cinemas and farms.
Human rights campaigners lashed out at the tough measures, labelling the plans "a nother chilling recipe for injustice".
But in her speech, Mrs May was adamant the legislation was vital.
"This legislation is important, the substance is right, the time is right and the way in which it has been developed is right," she said. " It is not a knee-jerk response to a sudden perceived threat. It is a properly-considered, thought-through set of proposals that will help to keep us safe at a time of very significant danger.
"We are engaged in a struggle that is fought on many fronts and in many forms. It is a struggle that will go on for many years.
"And the threat we face right now is perhaps greater than it ever has been - we must have the powers we need to defend ourselves."
A statutory duty will be placed on named organisations - such as colleges, universities, the police and probation providers - to help deter radicalisation and, where organisations fail, ministers will be able to issue court-enforced directions to them, the Home Secretary said.
Elsewhere, terrorism prevention and investigations measures (TPims) will be strengthened to re-introduce powers in Labour's control orders to relocate terror suspects around the country.
Police are to be handed powers in the new bill to force internet firms to hand over details that could help identify suspected terrorists and paedophiles, while p olice and border staff will be given the power to seize the passports of terror suspects.
Earlier, Britain's chief counter-terror police officer warned the current threat to the UK from jihadists will remain for "several years".
Scotland Yard's Assistant Commissioner Mark Rowley, the national policing lead for counter-terrorism, told a press conference the extremist threat will continue even if the violence in Syria and Iraq subsides.
Asked if the current terror climate would continue for at least five years, Mr Rowley said: "We have seen a step change that will sustain for many years.
"Even if the awfulness that's happening in Syria and Iraq was miraculously to get sorted in the next year or so - and that looks a very optimistic 'if' - there are other countries across parts of Africa and elsewhere in the world which are in parlous states and the potential for this type of terrorism to reach back into Europe to continue in other theatres is equally great.
"Whether it continues in that theatre or whether it moves into other places, I think there's a high prospect of it continuing in this nature for several years."
Yesterday, Scotland Yard commissioner Sir Bernard Hogan-Howe disclosed that "four or five" plots have been foiled this year.
The terror threat level in the UK was raised from substantial to severe a few months ago against a backdrop of increasing concerns over hundreds of aspiring British jihadis travelling to Iraq and Syria to learn terrorist ''tradecraft''.
IS-linked terrorist groups in Syria and Iraq have been using kidnappings to raise funds - with the UN estimating the tactic has brought in £28 million over the past year.
Mr Rowley told the awareness-campaign event that police officers and other law enforcement agencies "cannot succeed alone" in defeating the terror threat and urged the public and businesses to help.
He also revealed that through the Government's Prevent anti-radicalisation programme, counter-terror officers received 77 reports from families this year, some of which have enabled police to catch aspiring terrorists.
And the assistant commissioner said in recent months the police had seen a "substantial uplift" in suspicious activity reports.
Elsewhere in the UK, police officers and theatre groups will be speaking to students about the Prevent strategy, which provides help to stop people being radicalised.
Sniffer dogs will be hunting large amounts of money at ports, airports and railway stations to prevent cash leaving the UK for terrorist purposes.
Other events will follow, including work with farmers to ensure fertilisers - that can be adapted into explosives - are stored securely and charities to advise people about safe ways to donate money.
IS has posted a series of videos online showing the separate murders of US journalists James Foley and Steven Sotloff, US aid worker Peter Kassig and two British aid workers, David Haines and Alan Henning.
Footage claiming to show Mr Henning's murder appeared on the internet just days after the UK joined US-led air strikes against the terrorists in Iraq.
In addition, an IS fighter with a British accent has appeared unmasked in other films encouraging ''brothers'' in western countries to ''rise up'' and commit acts of terror in their home countries.
America's Federal Bureau of Investigation (FBI) has launched an appeal for the public's help in identifying individuals who have travelled - or are planning to travel - overseas to engage in combat alongside terrorist organisations.
Human rights groups raised concerns about the Government's new proposals.
Shami Chakrabarti, director of human rights group Liberty, said: " Yet again, politicians resort to high talk and rushed legislation in an attempt to look tough in the face of terrorism. Another chilling recipe for injustice and resentment by closing down the open society you seek to promote."
Amnesty International UK legal adviser Rachel Logan said: "Overall, it's worrying that the Government is intent on fast-tracking a whole host of potentially draconian new measures without - again - allowing proper time for Parliament to scrutinise them.
"It looks like a grab-bag of measures, none properly thought through."
And the Islamic Human Rights Commission (IHRC) criticised the week-long national police initiative to raise awareness about terrorism as "ill thought-out", warning it "only serve to further alienate Muslims".
IHRC chair Massoud Shadjareh said: "Government anti-terrorism policy is in total disarray and governed by the needs of foreign policy rather than the aim of preventing terrorism.
"The latest initiative is pumping the same failed Prevent agenda that is actually responsible for driving more people into extremist violence."
Deputy Prime Minister Nick Clegg said the Liberal Democrats had dropped their opposition to the strengthening of Tpims in the light of the increased threat faced by the UK.
"When you have a new threat you have to consider, sensibly, led by the evidence, whether the new threat requires a new response," he told reporters at his monthly press conference.
"If you see a new threat - and you have got hundreds of people who have gone from this country to fight in a bloody conflict in Syria and Iraq and with the prospect a significant number of them might seek to return and a fair number of those in turn might wish us harm - of course, like any reasonable person, any sensible government, any sensible politician, you work out whether we've got all the right defences in our armoury to deal with them."
The changes had been backed by an independent review, he pointed out - and its recommended safeguards incorporated.
"I think it is a balanced package. I have tried to do what is the right thing for the country which is keep us safe - and if necessary legislate to do so - but also to do so by keeping our values, our civil liberty values, safe.
"I would not be standing here endorsing the Counter-terrorism Bill ... if I wasn't confident it struck the right balance."
He said the IP address changes were "perfectly sensible" but accepted that Mrs May wanted to "go a whole lot further" and introduced the so-called "Snoopers' Charter" laws.
"I just think it's disproportionate, I don't think the British people would accept it and my party would never accept it."