A Muslim organisation from Leicestershire has urged people not to watch the brutal online video showing the beheading of British aid worker David Haines.
The Federation of Muslim Organisations (FMO) said it condemned the killing by the militant group Islamic State (IS or ISIS).
The terrorist organisation posted a video of the murder on YouTube.
But Suleman Nagdi, spokesman for the FMO, said people should not play into the hands of IS and watch the bloody execution.
He said: "We unequivocally condemn this brutal and savage murder and would urge everyone to refrain from viewing any video of this brutal act.
"David had gone to Syria to help co-ordinate the delivery of clean water, food and tents, in order to ease the growing humanitarian crisis in refugee camps near the Syrian border with Turkey.
"Our thoughts are with his family and loved ones including his young children."
In a statement put out by Downing Street, Prime Minister David Cameron said: "This is a despicable and appalling murder of an innocent aid worker. It is an act of pure evil."
Mr Cameron has called an emergency meeting to discuss the killing and is expected to make an announcement at midday.
