Police will be given temporary powers to seize passports at UK borders of Britons they suspect are travelling abroad to fight with terror groups, David Cameron has announced.
The Prime Minister also said the Government would "work up plans" for discretionary powers to exclude British nationals from the UK, telling MPs it was "abhorrent" that British citizens who pledge allegiance elsewhere were able to return to the UK and pose a threat to national security.
New powers will be introduced to bolster terrorism prevention and investigation measures (Tpims), including "stronger locational constraints", he said.
Mr Cameron said: "Adhering to British values is not an option or a choice. It is a duty for all those who live in these islands so we will stand up for our values, we will in the end defeat this extremism and we will secure our way of life for generations to come."
The plans to extend anti-terrorism powers come after a weekend of coalition negotiations following an increase in the terrorist threat to the UK from substantial to severe.
Mr Cameron said: "We will introduce new powers to add to our existing terrorism prevention and investigation measures including stronger locational constraints on suspects under Tpims either through enhanced use of exclusions zones or through relocation powers."
The Prime Minister dismissed suggestions by London mayor Boris Johnson that travel to certain countries should be criminalised as "wrong" but said measures were needed to stop some Britons returning.
Mr Cameron added: "We are clear in principle that what we need is a targeted discretionary power to allow us to exclude British nationals from the UK and we'll work proposals on this basis with our agencies in line with our international obligations and discuss the details on a cross-party basis."
Airlines will also be hit by tougher rules, including providing information on passenger lists, or their flights will be blocked from landing in the UK.
Labour leader Ed Miliband said relocation powers were a central part of the control order system that the coalition scrapped and replaced with Tpims.
"With regards to the most serious high-risk cases where convictions in the courts cannot be achieved I welcome your recognition that the Independent Reviewer on terrorism had made clear the inadequacies of Tpims," he said.
"In particular the inability to relocate suspects away from their communities.
"Relocation was indeed a central part of control orders and it was a mistake to get rid of them in the first place."
Mr Miliband also said Mr Cameron's proposals to exclude British nationals involved in terrorism abroad from entering the country were "unclear".
Mr Cameron and Deputy Prime Minister Nick Clegg were in ''constant communication'' over the last few days to find a compromise over the Government's response to dealing with the threat posed by Islamic State (IS) extremists.
Liberal Democrats were fiercely opposed to the control orders and while negotiations continued former leader Lord Ashdown warned that politicians should not act as "cheerleaders" for the demands of the intelligence and security services.
Liberty director Shami Chakrabarti said yesterday's announcement meant Tpims are now identical to control orders.
She said: "Sabre-rattling and thinly-veiled threats to the courts, but little detail from the Prime Minister.
"Why demand that the police seize passports on a discriminatory, dangerous basis rather than arrest those intent on committing murder?
"Control orders and Tpims become identical via internal exile at home, while the threat of external exile remains with the dangerous and innocent alike dumped like toxic waste on the international community."
Former Attorney General Dominic Grieve said it would be ''probably impossible'' for the Government to prevent Britons suspected of fighting for IS returning to the UK.
The Conservative MP told BBC Radio 4's PM programme: "Whilst the person who goes abroad fighting in Syria may technically commit treason, and indeed should be put on trial perhaps for treason when they come back, nevertheless they are British nationals and excluding them unconvicted from coming to this country raises severe difficulties."