Samsung halted business with Dongguan Shinyang Electronics after China Labor Watch found at least five child workers without contracts at the plant.
The kids were working on the assembly lines at Dongguan Shinyang and yet a month earlier an independent audit by Samsung found no child labour at the site.
Shinyang said that a third-party firm supplying workers had brought in child labourers around the end of June with forged identification.
There are no child workers at Dongguan Shinyang now and the children working at the plant have been let go.
Samsung suppliers have been under watch since 2012, when China Labor Watch found seven children younger than 16 were working for one of the South Korean firm’s China-based suppliers. Chinese law forbids hiring workers under 16.
Apple had a similar problem with some of its Chinese contacts and people objecting to Foxconn workers throwing themselves off buildings rather than making its shiny toys.