Dutch police say some 300 children are being exploited across Europe by gangs that force them to steal €1,000 (£770; $1,100) a day.
Four networks were uncovered operating in the Netherlands, Spain, Austria, Croatia and Bosnia, police said.
Six missing children from the Netherlands were found in appalling conditions in Spain last week when a couple in their 40s were arrested.
Prosecutors say the practice is a modern type of slavery.
The operation began over a year ago when investigators at Amsterdam Central Station noticed that a group of children were being used repeatedly as pickpockets under the control of adults, said a police statement (in Dutch).
Children were taken out of school to carry out shoplifting and pickpocketing, and authorities believe under-age girls were sexually abused and became pregnant.
When police arrested the Eastern European couple in a raid on a flat in the Spanish city of Barcelona on 15 June, they found a baby and five other children under the age of 15.
‘Tip of the iceberg’
The couple are thought to be part of a child exploitation network and are expected to be extradited to the Netherlands. They are suspected of people trafficking, using false identities and removing underage children from competent authorities.
According to Dutch media, some of the children were under youth protection supervision and had previously been reported missing from an asylum seeker centre in Ter Apel in the north-eastern Netherlands.
“These days we look at whether a child is a victim of people trafficking,” said prosecutor Warner ten Kate.
“I feel that this is the tip of the iceberg, that there are more children in the Netherlands who are victims of this.”
Police believe the children had come from poor families in Bosnia and other countries in the former Yugoslavia.