British citizens have posted video footage and photographs that suggest they have been involved in the torture and murder of prisoners during the civil war in Syria, it was reported.

A man, who is believed to be with a jihadist rebel group, claimed to have beaten a fighter from the Free Syrian Army (FSA), which is backed by the West, according to The Times. The injured man was shown tied to a car tyre and being hit with an iron bar in footage posted on the internet.

“This FSA scum never thought we wud jump out at them and pick them up after saying some abusive words to our brothers,” the British man wrote. “Two then got ahead of themselves and swore at Allah, at this point there was no stopping us LOL [laugh out loud] although we where told to jus leave them.”

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Three blindfolded prisoners were pictured in a post on Twitter. “Got these criminals today. Insha’Allah [God willing] they will be killed tomorrow. can’t wait for that feeling when you just killed someone,” the accompanying text said.

The same poster later tweeted a picture showing a hand dripping with blood with the words, “My first time!”

Shiraz Maher, a senior fellow at the International Centre for the Study of Radicalisation at King’s College London, said the man who posted the video footage was from London and had been to university.

“He is a known British jihadi and we have been monitoring him and his account and his grouping,” he said.

Mr Maher said he had contacted the man over the internet. The man denied killing prisoners and said the blood on his hands was from a sheep that had been slaughtered.