Samsung Electronics Co Ltd said it will do 30 percent less business with a parts supplier after discovering child workers at the China-based firm, marking the IT giant's strongest objection to the illegal practice to date.

In July, the South Korean company suspended business with Dongguan Shinyang Electronics Co Ltd after at least five child workers without contracts were reported to be employed by the Guangdong-based company.

Samsung said Chinese authorities discovered that while Dongguan Shinyang did not directly employ underage workers, a subcontractor had hired them through a labor dispatch agency.