Samsung Electronics said Thursday it was urgently investigating allegations that its Chinese supplier Shinyang Electronics had hired at least five workers under the age of 16.

"We will take appropriate measures in accordance with our policies to prevent any cases of child labor in our suppliers," the South Korean technology firm said in a statement released Thursday.

Samsung said it was pursuing a zero tolerance policy on child labor, and that the supplier had been subject to a series of audits in which no cases of child labor had been found.

Samsung's probe follows fresh allegations by US-based rights group China Labor Watch (CLW), claiming that children were hired by Shinyang during busy production periods. The children were forced to work 11 hours a day without overtime pay and without social insurance, CLW said, adding that they usually left production after three to six months, without severance pay.

CLW's report is in stark contrast to a Samsung-commissioned study carried out by an independent auditing firm in 2013 and 2014. The auditors didn't find evidence of the use of child labor, but they found that excessive working hours are commonplace among Samsung suppliers. They also identified 59 suppliers that failed to supply safety equipment to workers.

On Thursday, CLW Executive Director Li Qiang described the audits as inaccurate. He called Samsung's monitoring system ineffective, and said it had failed to bring about improvements for workers.

In 2012, China Labor Watch accused Chinese tech suppliers which supply smartphones for Samsung and Apple of inhumane working conditions, including excessive overtime and the use of child labor. At the time, Samsung promised to introduce a new hiring process and sever ties to companies that continued to violate its code of conduct on child labor.

uhe/nz (AP, dpa, AFP)