A 16-year-old boy whose two elder brothers have been killed waging jihad in war-torn Syria has been barred by a High Court judge from travelling abroad.
Mr Justice Hayden made the teenager a ward of court - a move which bars him from leaving the jurisdiction of England and Wales.
The judge made the ruling at a hearing in the Family Division of the High Court in London after local authority social services staff raised fears that the teenager could travel to Syria.
He said the youngster could not be named.
But he said the local authority which had applied for the teenager to be made a ward of court was Brighton and Hove City Council.
Mr Justice Hayden was told that the teenager had joint Libyan and British nationality.
He was told that council staff had learned that family members were making plans for the teenager to go on a trip to Dubai during the Easter holiday.
The judge said he was concerned to "keep this lad alive" and said an order which barred from travelling abroad was proportionate.
"(The teenager) is a vulnerable young person," said the judge. "He has grown up in modern Britain in an extraordinary family - a family where the male members are patently committed to waging Jihad in war-torn Syria."
He said he had balanced the teenager's human rights and added: "The balance falls clearly in protecting this young man, ultimately from himself."
A lawyer representing the council said the teenager's family had an "extraordinary history".
Barrister Martin Downs said the boy had an uncle who had been held in United States' detention camp in Guantanamo Bay, Cuba.
He said three of the boy's brothers had gone to fight for the al-Nusra Front - a group with links to al-Qaeda.
Two had died when both in their teens - the third had been wounded but was still fighting in Syria.
A friend of the teenager had also been killed in fighting.
The judge, who said the four fighters could not be named, added: "The local authority's anxiety here is that (the teenager) may wish to follow the path which his brothers have walked."
Lawyers told the judge that the teenager lived with his mother.
Mr Justice Hayden said she was "exhausted by grief" and there were concerns that she was unable to place "proper boundaries" around him.
He said the council had considered asking for the teenager to be taken into care. But given the boy's age, staff thought making him a ward of court would be a better option.
The judge said by becoming a ward of court the youngster would come under the protection of a judge and added: "A child who is a ward of court may not be removed from England and Wales without the court's permission."
Lawyers said it was thought this was the first time a family court judge had been asked to take such an approach to prevent a boy going to fight in Syria.