US forces have carried out an air strike targeting the Islamic State group militant "Jihadi John", with a "high degree of certainty" he was hit.

Mohammed Emwazi, the Kuwaiti-born British militant, appeared in videos of the beheadings of Western hostages.

It is believed there was at least one other person in the vehicle targeted in the attack near Raqqa, in Syria.

The UK government said it was "working hand in glove with the Americans" to "hunt down those murdering hostages".

A US official told the BBC Emwazi had been "tracked carefully over a period of time".

Another senior military source said there was a "high degree of certainty" he had been killed, while another source said: "It was a great hit."