Police who returned a passport to a Bristol teenager thought to be at risk of travelling to an Islamic State-held area have been rebuked by a judge.
The passport was seized in April, when the girl was stopped at Bristol Airport with a one-way ticket to Turkey.
But officers returned it a few days ago, believing they were not allowed to keep it for longer than two weeks.
High Court judge Mr Justice Hayden said police could have addressed the issue by taking civil court action.
At a hearing in the Family Division of the High Court in London, Mr Justice Hayden made the girl a ward of court – a move that prevents her from travelling abroad without a judge’s permission.
He also ruled the passport must again be taken from her and directed that the girl – who is of Somali origin – was not identified.
The hearing comes after social services staff involved with the girl’s family raised concerns.
The judge stressed that counter-terrorism officers working with radicalised Muslim teenagers faced an “immense challenge”.
But he said he wanted to ensure that units across the UK understood the options available.
“The police, quite wrongly in my view, took the view that they were constrained to return the passport. They were not,” he said.
“An immediate telephone application (to the High Court) could have been made.”
The officers involved are members of the South West Counter Terrorism Intelligence Unit.
The girl is one of a number of teenagers thought to be at risk of travelling to areas controlled by Islamic State who have been grounded by judges in recent months.
Teenagers who have been made wards of court include four girls from London who attend the same school, Bethnal Green Academy in east London, as three girls already thought to have fled.