Speaking for the first time in detail about his three sons' decision to join extremist groups fighting in Syria, Abubaker Deghayes, 45, said, "Amer, Jaffar, if you see me or this interview please, please come back home. Enough. This war has taken away Abdullah already … I'd like to see you live longer," the British daily Guardian wrote in a report.

Jaffar, 16, is the youngest named Briton known to be fighting in the foreign-charged war in Syria.

Deghayes said he did not fear prosecution from the UK authorities over his role in his sons' decisions to join extremist groups but admitted that he had failed as a father to persuade them to return home after travelling to Turkey to stop them.

Estranged from his children after social services accused him of being violent towards them, Abubaker said that his eldest son, Amer, 20, had been in Syria since early December after leaving his job and studies in Brighton.

"He went out openly … in a convoy to Syria. I thought I'd managed to talk him into helping by taking aid, taking medicine."

Deghayes, a property lettings manager in Saltdean, who said he had twice been to Syria on humanitarian relief efforts, told the Guardian that it had not been long before Amer told him he had joined the al-Qaeda’s al-Nusra Front.

"He was always saying, 'I want to join, I want to fight' … he was determined."

In February, his daughter told him that his two other sons – Abdullah, who was killed a week and a half ago, and Jaffar – were missing with their passports.

Deghayes said he travelled to a border town in Turkey and tracked them down to dissuade them from fighting.

"I said [to them] 'why are you going there, it's not worth it, you have to stick to helping in the refugee camps and doing the humanitarian work'."

"I didn't argue with them. I knew arguing would make them more stubborn. I spoke to them nicely and tried to convince them … If you argue, they just leave you and go." But they remained unmoved. "I failed to bring them back."

"I am scared for my children. I don't want to lose them obviously. But they are becoming men now."

Deghayes said when he first saw a picture of his dead son last week he felt shocked and saddened, but added that his son who was fighting for terrorist al-Nusra Front was a martyr.

Deghayes said that growing up, all his sons had been affected by the family's campaign to free his uncle, Omar, who was imprisoned in Guantánamo bay.

"We had a lot of attacks on our house, from people who took the other side, 'Their uncle is a terrorist'. That impacted on all our children. And they were always called names, 'Taliban, terrorist' because of the campaign."

He said the living room window at his detached house had been broken four times and the police had failed to make arrests when groups of 15 to 20 demonstrators turned up outside shouting abuse.

He said his sons' studies had been thrown into turmoil as a result. "Every day I had phone calls from school, it was a very sad story. I tried to get them to concentrate on education but we never got to that stage. We were always in a process where there's some problem, either detention or exclusion.''

Abdullah's identical twin Abdulrahman, who is still in Brighton, was very upset. "He's sad and crying because of the loss of his brother.

Asked if he thought Abdullah's life had been wasted he said, "I'd say he had a short life. I'm talking to you from my belief which is Islam. Everyone has a set time to live in this universe … I wouldn't say wasted, no. I hope he died for something good … I don't want to think that his life was wasted."

Deghayes said that young British Muslims should not follow his son out to fight. "Syrians have enough men to fight … they're not short of men for my son to go, for anybody from Britain to go”.

Thousands of foreign militants, including hundreds of Britons, are now in Syria according to government sources.

A British defense study published last September showed that about 100,000 militants, fragmented into 1,000 groups, were operating inside Syria and carrying out atrocities against people and Syrian soldiers.

According to the study, some 10,000 militants were fighting for groups affiliated with al-Qaeda and the rest fight for different militant groups.

They are highly feared as they gain combat experience and forge connections with extremists while many experts warn they could return radicalized and seek to carry out attacks against the West.

SHI/SHI