The UK’s terror threat level has been raised from “substantial” to “severe” in response to conflicts in Iraq and Syria, Home Secretary Theresa May says.
The new alert level rates the risk of an attack on the UK “highly likely”, although Mrs May said there was no evidence to suggest one was “imminent”.
It is the second highest of five possible UK threat levels.
David Cameron promised new legislation would make it easier to take passports from those travelling abroad to fight.
The home secretary already has the power, under the Royal Prerogative, to withhold a passport if it is in the public interest to stop somebody travelling.