A government spokesperson has backed comments by a minister who said "in almost every case" British Islamic State fighters in Syria and Iraq must be killed.
Speaking on BBC Radio 5 Live's Pienaar's Politics, International Development Minister Rory Stewart said IS militants adhere to an "extremely hateful doctrine" and “the only way of dealing with them will be, in almost every case, to kill them."
Responding to Stewart's comments, a government spokesman said they are in line with the stated position of Defence Secretary Sir Michael Fallon, who earlier this month told British IS fighters: "You have made yourself a legitimate target and run the risk, every hour of every day, of being on the wrong end of an RAF or USAF missile".
The spokesman added: "Nobody should be in any doubt about our determination to fight and defeat Daesh terrorists, regardless of nationality.
"Anyone who does travel to Syria, for whatever reason, is putting themselves in considerable danger - particularly if they are fighting for our enemies."
Stewart was responding to a question about Brett McGurk, a US envoy for the coalition fighting Islamic State, who said his mission is to ensure all foreign fighters in Syria are killed.
"These are people who have essentially moved away from any kind of allegiance towards the British Government,“ Stewart said.
"They are absolutely dedicated, as members of the Islamic State, towards the creation of a caliphate, they believe in an extremely hateful doctrine which involves killing themselves, killing others and trying to use violence and brutality to create an eighth century, or seventh century, state.
"So I'm afraid we have to be serious about the fact these people are a serious danger to us, and unfortunately the only way of dealing with them will be, in almost every case, to kill them."
The former diplomat went on to say: "These are people who are executing people in the back of their heads, who have held women and children hostage, who are torturing and murdering, trying by violence to impose their will.
"Our response has to be, when somebody does that, I'm afraid, to deal with that."
Stewart also said it remained British policy to remove Syrian President Bashar al-Assad. "I don't think anyone should be in any doubt that the control that he has is brutal and ultimately fragile," he said.
"The policy of the British Government is that Bashar al-Assad needs to step aside and we need transition to a new government, because so long as that man is in power, it is going to be impossible to have a long-term, stable, sustainable future for Syria."