An Afghan boy found alone at Heathrow Airport must go into council care in England, the High Court has ruled.
The boy, aged about 12, said the trip had been "planned and paid for" by his mother who thought he would have a "better and safer" life in the UK.
After his discovery at the airport, the boy was temporarily placed in foster care by council social services staff.
Mrs Justice Theis has now ruled it would be impossible to return him as it is not known where his mother is.
Details of the case emerged in a ruling by Mrs Justice Theis following a family court hearing in London.
'Impossible to return'
Social services bosses at Hillingdon Council had brought the case before her.
"There is some uncertainty as to precisely how he arrived at Heathrow Airport, and what methods of transport he had between Afghanistan and the United Kingdom," said the judge.
"The whereabouts of his mother are unknown and it would be impossible to return [him] to her care in Afghanistan at this time."
The judge said she had been asked to decide how the boy's welfare interests could best be met.
She added it was up to Home Office officials to make decisions about his immigration status.