Seven Romanian children between the ages of nine and fifteen have been found working on a farm in Worcestershire.
The Gang Masters Licensing Authority (GLA) and West Mercia Police followed up a tip off to find the children, two boys and five girls, picking spring onions last week.
In a total a group of 50 Romanians were working in the field where 'no licensed gangmaster could be established'. Some of the children were working with their parents but others were not.
The GLA said that none of the workers were dressed adequately to protect themselves from the freezing conditions.
West Mercia Police took the children into Police Protection and further enquiries are ongoing by the GLA, Police and UK Border Agency.
One of the vehicles seen to bring workers to the field was a box van with a settee in the back, said a GLA spokeman.
A member of the GLA team confirmed that this was the first time the authority had found children working in fields anywhere across the UK.