Twitter and Facebook have taken steps to close down the accounts of militant Islamic State supporters after the publication of a video that appeared to show a man with a British accent "beheading" the American journalist James Foley.
The video is thought to have first surfaced on an account called @mujahid4life which was purportedly run by a convert to Islam who describes himself as "anti-democracy, loyal to the Caliphate, harsh on kuffar".
This account has now been belatedly blocked, even though it had promoted violent jihad in the name of the Middle Eastern terrorist organisation Islamic State, formerly known as the Islamic State of Iraq and Syria (ISIS), for several months.
@mujahid4life's owner calls himself Abdullah and has previously tweeted all manner of violent suggestions, as well as issuing bizarre proclamations about his love for the Robin Williams film Jumanji.
The brutal video of what appears to be Foley's murder was uploaded to YouTube, with members of an Islamist forum reportedly urging supporters to keep posting it in a bid to terrorise Americans.
“We must upload the video with a title in both Arabic and English for it to arrive to the American people," a poster on the Hanein forums wrote. "Keep uploading the video every minute since YouTube declared war on us your brothers.”
However, the Google-owned video site has now taken steps to remove the content.
"YouTube has clear policies that prohibit content like gratuitous violence, hate speech and incitement to commit violent acts, and we remove videos violating these policies when flagged by our users," a spokesperson for YouTube said. "We also terminate any account registered by a member of a designated Foreign Terrorist Organization and used in an official capacity to further its interests."
Twitter users have started to use the hashtag #ISISmediaBlackout in a bid to discourage the sharing of Islamist militant propaganda. The hashtag has been shared more than 7,000 times, according to figures from the analytics firm Topsy.
However, the footage is still available for viewing on LiveLeak, where it has been viewed more than 5,000 times. It does not show the actual "beheading," but instead features the British-accented man railing against US President Obama for launching air strikes against the Islamic State and the cuts to a picture of what appears to be a headless body. The man purportedly carrying out the beheading speaks in what sounds like a London accent.
At the end of the video, the jihadi is shown alongside another captured journalist, Steven Joel Sotloff, who is wearing an orange jumpsuit. He had filed articles for publications including Time before being kidnapped near the border between Syria and Turkey on 4 August 2013.
"The life of this American prisoner, Obama, depends on your next decision," the black-robe-clad man says.
The video nasty has not yet been fully verified. Caitlin Hayden, a spokeswoman for the US National Security Council, said: “We have seen a video that purports to be the murder of US citizen James Foley by ISIL. The intelligence community is working as quickly as possible to determine its authenticity.
"If genuine, we are appalled by the brutal murder of an innocent American journalist and we express our deepest condolences to his family and friends. We will provide more information when it is available."
The microblogging site has also promised to remove anyone sharing images of the atrocity. Twitter's Dick Costolo tweeted the following warning:
We have been and are actively suspending accounts as we discover them related to this graphic imagery. Thank you https://t.co/jaYQBKVbBF— dick costolo (@dickc) August 20, 2014