Chinese schoolchildren worked illegal overtime and night shifts to produce smart speakers for Amazon, according to leaked documents seen by the U.K.'s Guardian newspaper.
Amazon supplier Foxconn confirmed to CNBC Friday that it had been alerted to violations of Chinese labor laws at its facility in the southern city of Hengyang.
The Guardian reported Thursday that interviews and leaked documents showed hundreds of schoolchildren — classified by the factory as interns — had been hired by Foxconn to produce Amazon's smart devices.
According to the report, teenagers were working overtime and night shifts to reach manufacturing quotas for Amazon's Echo, Echo Dot and Kindle products.
Teachers were reportedly paid to accompany children to work and asked to encourage "uncooperative" students to take on additional overtime.
While Chinese labor laws allow the employment of juvenile workers aged between 16 and 18, it's illegal for them to work night shifts or overtime.
In an emailed statement, Foxconn Technology Group told CNBC the company had a long-running, short-term internship program it carried out in partnership with local governments and vocational schools in China, which offered workers "competitive" salaries and benefits.
"We regularly carry out internal reviews of this program and a recent review of our operations in Hengyang determined that we were not in full compliance with all relevant laws and regulation," a spokesperson said. "In cooperation with the Foxconn Labor Union in that facility, we are working to address those areas where deficiencies have been noted."
The firm added that it had doubled monitoring of the internship program and was increasing the recruitment of full-time staff to reduce the requirement for workers to be dispatched from elsewhere.
Meanwhile, a spokesperson for Amazon said in an email that the tech giant regularly assessed its suppliers using independent auditors.
"If we find violations, we take appropriate steps, including requesting immediate corrective action," the spokesperson said.
"We are urgently investigating these allegations and addressing this with Foxconn at the most senior level. Additional teams of specialists arrived on-site yesterday to investigate, and we've initiated weekly audits of this issue."
More than 1,000 juvenile workers are employed at Foxconn's Hengyang facility, the Guardian reported.
Foxconn also makes products for U.S. tech giant Apple.