Islamic State militants fighting in Iraq and Syria released a video on Saturday which purported to show the beheading of British aid worker David Haines, Reuters reported.
Reuters could not immediately verify the footage. However, the images were consistent with that of the filmed executions of two American journalists, James Foley and Steven Sotloff, in the past month.
Haines, a 44-year-old father of two from Perth in Scotland, was kidnapped last year while working for the French agency ACTED.
The video entitled, "A Message to the Allies of America," opened with UK Prime Minister David Cameron talking about working with the Iraqi government and allied Kurdish Peshmerga forces to defeat Islamic State.
"This British man has to pay the price for your promise, Cameron, to arm the Peshmerga against the Islamic State," said a masked man dressed in black with a British accent, standing over Haines, who was shown kneeling and wearing an orange jumpsuit.
The video then showed the beheading of the kneeling man.
At the end of the video, another hostage was shown and the masked man said he would be killed if Cameron continues to support the fight against Islamic State.