Islamic State militants have issued an apology to their fellow jihadis for accidentally posting the video of Steven Sotloff’s beheading early.
The gory footage emerged online on Tuesday night, two weeks after the almost identical murder of another American journalist, James Foley.
It was apparently released ahead of the agreed time on a Twitter account that has since been suspended and the planned publication date for the footage is not known.
In a sign of disorganisation in the extremist group's ranks, a faction of Isis later apologised and asked fellow jihadis not to “reproach” them.
The video was first released on the @AlBattr88 account, Vocativ reported, and by the time another Isis-affiliated profile, @Khattabyaz pointed out their mistake, it was already circulating.
The group then apologised in Arabic on the site Justpaste, saying: “A clarification about the mistake was made by 'Uyun al-Ummah' account, that has published the video before the official time.
Video: Philip Hammond on IS and British hostage
“The user saw a tweet with the video and thought it was published officially.
“We tried to remove the video after we understood that his was published by mistake and we are sorry to the followers of the Islamic State.”
The footage shows Mr Sotloff kneeling in the desert reading a scripted message about military action by the US and Western allies in Iraq before being beheaded.
Philip Hammond, the Foreign Secretary, has confirmed that his killer is the same British terrorist who murdered Mr Foley last month.
Mr Sotloff was a freelancer who had contributed to magazines including Time, The Christian Science Monitor and Foreign Policy, reporting from conflict zones across the Middle East and North Africa before he was abducted near Aleppo in August 2013.
In pictures: Steven Sotloff
In pictures: Steven Sotloff
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Steven Sotloff inside Al-Fateh Mosque in Manama, Bahrain, in 2010
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Journalist Steven Sotloff, left, pictured in Libya in 2011
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Steven Sotloff pictured in 2010 near Lulu Roundabout in Manama, which later became the iconic center for the 2011 pro-reform protests in Bahrain
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Journalist Steven Sotloff pictured in Egypt
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Media gather outside Steven Sotloff's family home in Pinecrest, Florida
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Shirley Sotloff during a recent appeal to the captors of her son
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Pinecrest police officers are positioned at the home of Arthur B. Sotloff and Shirley Sotloff, the parents of American freelance journalist Steven Sotloff, in Pinecrest, Florida
His mother, Shirley Sotloff, had begged the self-proclaimed caliph of Isis’s “Islamic State” to show mercy and release her son.
She said the 31-year-old travelled to Syria to cover the “suffering of Muslims at the hands of tyrants” before he was abducted near Aleppo in August 2013.
“He is an honourable man and has always tried to help the weak,” she said.
“Stephen has no control over the actions of the US government. He's an innocent journalist.”
Isis has threatened to kill a British hostage, who was paraded in front of the camera, if the US and Western allies do not “back off” from military action against its fighters in Iraq.