A 10-year-old boy who has cancer in his jaw and needs "urgent surgery" has vanished, a High Court judge has said.
The youngster, who has not been identified, is Polish and could be in Poland with his parents, Mr Justice Mostyn said.
Detail of the boy's case emerged today in a ruling by the judge following hearings in the Family Division of the High Court in London.
A doctor has told the judge that the boy will die a "brutal and agonising death" within six months to a year if a tumour is not removed "very soon".
Mr Justice Mostyn said the Polish embassy in London was being alerted.
And he urged the boy's parents to co-operate with doctors.
The judge said there was evidence that the youngster had left his home in England with his mother two weeks ago, and evidence that the boy's father had boarded a ferry bound for France in the last few days.
He said the boy was at risk of "serious harm" and the risk was growing with every day that passed.
Mr Justice Mostyn said he had made an order saying efforts should be made to find the boy.
He said it was possible that the boy, who had lived in England with his parents for two years, was in Poland.