The number of children arrested for drug dealing has reportedly risen by more than a quarter over the last five years.
A total of 2,097 under-18s were detained last year for supplying drugs or possession with intent to supply, compared with 1,639 in 2013, according to figures quoted in the Guardian.
The figures, obtained through Freedom of Information requests, cover 24 of the 43 police forces in England and Wales.
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Five forces provided data for under-16s, which showed drug dealing arrests had almost doubled during the same time period, from 157 to 312.
Children as young as 12 were reportedly arrested for possession with intent to supply drugs such as heroin and crack cocaine.
The rising numbers have prompted concerns about young people being exploited by gangs to sell drugs in out-of-town areas - a practice known as 'county lines'.
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DS Ken Lamont, of Devon and Cornwall Police, told The Guardian that county lines trading was a contributing factor in the rise in arrests.
"At the moment I wouldn't say [county lines trading] is endemic but it's certainly a problem and we have done significant disruptions," he said.
Rhiannon Sawyer, the Children's Society's area manager for children and young people's services in Greater London, told the paper her staff had noticed more children being targeted to deal drugs, some as young as 12.
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"They are more vulnerable as they are younger and the rise is significant enough to get us worried about it," she said.
"The level of violence (around county lines trading) is getting worse."