More than 2,000 primary school children were arrested in England and Wales last year.
Frances Crook, the chief executive of the Howard League for Penal Reform, told Today presenter John Humphrys that this is "very unacceptable" because being arrested is "very traumatic".
"This has very serious implications to the life of a child," she added.
"Most of [the cases] are naughtiness... this is the kind of stuff that should be dealt with by parents or schools."
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