Jihadi John tops secret 'kill list' of five Isil extremists
British terrorists on secret 'hit list' for assassination
Up to 10 British terrorists are thought to be on a secret list of people to be legally targeted for assassination by UK forces.
It is also understood that Mohammed Emwazi, identified as 'Jihadi John', is at the top of the list.
The men are all connected to a London terror cell whose most notorious member is Mohammed Emwazi, the real name of the Islamic State of Iraq and the Levant (Isil) executioner accused of beheading dozens of hostages, including Britons David Haines and Alan Henning.
The news came after two British jihadis were killed by an RAF drone strike in a war zone for the first time.
Ruhul Amin and Reyaad Khan were killed when the car in which they were travelling was hit in Raqqa, in Northern Syria, by a drone controlled from Lincolnshire.
British Defence Secretary Michael Fallon has refused to be drawn on the number of terrorists planning attacks against Britain but said it was more than three, and revealed plots were also uncovered against Australia and the US.
He said: "It's extremely dangerous because these are attacks that have been and are being planned against major public events on our streets. They are potentially attacks on members of our armed forces and on others, which would be extremely dangerous and would obviously involve the loss of life.
"Government has a duty, where it has information and the ability to prevent such attacks, government has a duty to deal with it."
Emwazi revealed his face for the first time last month and vowed to return to Britain, according to reports.
The cowardly killer, who was named earlier this year, is thought to have appeared in a video clip without his trademark black balaclava. However, legal expert David Allen Green yesterday used an article in the 'Financial Times' to raise his concerns about the legality of the drone attack.
He wrote: "When someone is killed by state action 'who deserves it' then it is always tempting to convert one's normative view into a positive statement that the death was lawful.
"But for me, the legal problem with the killing of Reyaad Khan is that to invoke Article 51 of the Charter is to perhaps push 'self-defence' beyond the limits of elasticity.
"Article 51 is not a general 'licence to kill' terrorists on sight wherever in the world they may be found - a 'licence' here meaning something which permits an action which would otherwise be unlawful.
"Some may say that the UK government should have such a licence to kill; but that is not what the law actually says.
"For me, this killing prompts various questions. What are the limits of 'self-defence' when faced with international terrorism?
"Is the contention that any pre-emptive attack can be justified if the target is a terrorist? When does 'self-defence' simply merge with a 'shoot to kill' policy?
"In 1988, the UK government sanctioned the killing of three IRA terrorists in Gibraltar.
"It must have seemed a good idea to the UK government at the time; but under scrutiny the UK government's account of what happened unravelled. Indeed, the UK government (and the security and police forces) do not have a great track record when pleading 'terrorism' when killing people.
"There is a good reason why life and death should not depend on the executive's fiat."