Colouring books were among the items police removed in searches
The stop and search of 11-year-old twins at the Kingsnorth Climate Camp was unlawful, Kent police have admitted at London's High Court.
The twins, referred to as E and T, were searched while at a demonstration against Kingsnorth coal-fired power station in August 2008.
Officers searched the twins on the grounds of "reasonable suspicion" they might be carrying prohibited articles.
The police admitted that officers at the scene had misapplied legislation.
The children were taken by their mother to the protest over plans for a new coal-fired power station.
The court heard T was left "crying and shaking" after a female officer said he had to be searched.
He feared he would "go to prison" because he had stickers in his bag, which other people had had confiscated.
Stickers, environmental badges, crayons, highlighter pens and a clown's wig were all confiscated by officers, according to the twins' mother.
Richard Perks, appearing for the chief constable of Kent Police, said the police accepted that the twins were unlawfully stopped and that officers on the ground had misapplied stop and search legislation.
To perform a search police must complete a form explaining the reason for it, but the court heard that officers had only written "Oasis Kent" and "D" on the slips relating to the twins' search.
Long-standing environmental campaigner David Morris, from north London, was also at the court and said he was forcibly searched against his will.
All three are seeking judicial review into police powers and potential damages.
The case has been adjourned while further evidence is considered before a settlement is reached or a full court hearing is called for.
All three were among 1,000 protesters at the camp near Hoo in August 2008.