Prime Minister David Cameron has welcomed the reported killing of the British terrorist known as Jihadi John in an air strike by US military as "a strike at the heart" of terror group Islamic State (IS).
Mr Cameron said it had not yet been confirmed that Mohammed Emwazi - who he branded a "barbaric murderer" - was dead.
But he said Britain had been working "hand in glove" round the clock with its closest ally the US to track down and target the militant, who is believed to be responsible for the deaths of several IS hostages, including Britons Alan Henning and David Haines.
In a statement outside 10 Downing Street, the Prime Minister said that Emwazi had remained a threat to innocent people, including in the UK.
And he said: "This was an act of self defence. It was the right thing to do."