The father of a British student seen in an ISIS recruitment video appealing for Muslims to join the fight in Iraq has pleaded with him to come home.
Ahmed Muthana told Sky News he believes his son Nasser was radicalised in a mosque in the United Kingdom, but did not know which one.
He said: "The way he talks is not Nasser talking, it's someone else … He was a very soft person, he was very nice, but why he left his family I don't know. Who drove him? I don't know.
"The way he talks, the radicalism he is talking about, recruiting, asking British-born Muslims to come Syria is not Nasser's way.
"Nasser has never persuaded anybody like this before. It's the first time for me and devastating for me and my family."
The 20-year-old is seen in the video - released on social media - wearing a white turban and using the name Abu Muthanna al Yemeni.
ISIS fighters have taken control of large areas of Iraq In the film, entitled "There is no life without Jihad", he claims the Islamic State in Iraq and Syria (ISIS), has fighters from as far afield as Cambodia, Australia and the UK.
His family, from the Cardiff area, said that he travelled to join the conflict with younger brother Aseel Muthana, 17.
Muthana is one of three apparent Britons to feature in the video, which calls for their countrymen to "answer the call and fight for Allah".
When asked if he had a message for his son, Mr Muthana said: "My message to Nasser and Aseel is please come back home.
"Your home is the United Kingdom, not the Middle East."
ISIS, which has taken over large parts of Iraq in recent weeks, has launched a global campaign asking Muslims to post messages "to support the Islamic State" on social media.
The three apparent Britons that appear in the video The militants have used it to release videos of them parading around towns they have claimed in northern Iraq.
One of the co-founders of Twitter has told Sky News the platform remains a "force for good" despite being utilised by groups such as ISIS.
Biz Stone told Digital View: "When you create a large-scale platform where hundreds of millions of people have the freedom of expression you have to take the good with the bad.
"I'd rather this sort of thing be out in the open than hidden in the back waters."
The Home Office said in a statement: "We do not tolerate the existence of online terrorist and extremist propaganda, which directly influences people who are vulnerable to radicalisation.
"We already work closely with the internet industry to remove terrorist material hosted in the UK or overseas."
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