Samsung Electronics Co has said it is "urgently" investigating allegations that one of its suppliers in China employed children and underage students.
China Labor Watch (CLW) said the supplier, Shinyang Electronics, was believed to have hired at least five workers under the age of 16.
The New York-based watchdog cited other violations, including unpaid overtime wages, excessive overtime and a lack of social insurance and training.
"We are urgently looking into the latest allegations and will take appropriate measures in accordance with our policies to prevent any cases of child labour in our suppliers," the South Korean Electronics giant said in a statement.
"We strictly maintain a zero tolerance policy on child labour," it said, adding that the supplier in question had been subject to a series of audits and inspections in 2013 and earlier this year.
"No cases of child labour were found," it said.
China Labor Watch called Samsung's monitoring system "ineffective".