A teenage girl from a Muslim family contacted a children's charity and said she and her siblings had been forced to leave their home in England and travel to north Africa by their mother, a family court judge has been told.
The girl, who is now in her late teens, said her mother was forcing her to marry and told how she feared for her life, Judge Claire Jakens heard.
She said an uncle was behaving in a "controlling" way and trying to "influence" them to "conform to a more Muslim way of life".
The girl, her brother, who is in his early teens, and sister, who is approaching her teens, had returned to England about two months later.
Council social workers with responsibility for the youngsters' welfare had launched family court litigation.
Judge Jakens has outlined detail in a ruling after analysing the case at a family court hearing in Brighton, East Sussex.
The judge has not identified the family involved but said they originated from north Africa and had lived in the Brighton area for some years.
She said the three children had been born in England.
Judge Jakens did not identify the north African country the children had been to.
The judge said police had investigated but indicated that no-one had been charged with any offence.
She said the children, who were now living with relatives, had gone through a "very strange and disturbing experience" and suffered "significant harm".
The judge said the children had been taken to north Africa in the spring of 2018 and returned to England during the summer.
She said about a month after arriving in north Africa the three youngsters had run away from their mother and gone to a British embassy.
The judge said embassy staff had handed the youngsters to local police who had returned them to their mother.
A Foreign Office official had made a statement saying it was not "within the diplomatic remit" to "act against applicable local laws", she said.
Social workers at Brighton and Hove City Council had asked the judge to make findings of fact to help them take decisions about future care.
Judge Jakens made a series of findings, including that the children's mother had threatened to "marry off" her teenage daughter.
She also said it was likely that the children's uncle smacked the younger girl for "speaking English".
Judge Jakens said forced marriage protection orders had also been made.
The judge said the family had been known to social services staff for around a decade.
She said they had also been "on the radar" for "culture-specific issues" because of fears that a third, older, daughter might travel to Syria.
