Foxconn, a main supplier for Apple's iPhone, says it has stopped interns from working illegal overtime at its factory in China.
High-school students hired to assemble iPhone X devices by Apple manufacturing partner Foxconn, illegally worked overtime hours at a plant in China, Apple has acknowledged.
According to a report by the Financial Times, at least six students from a group of 3,000 from a vocational school sent to work at the iPhone X factory in Zhengzhou, China.
The report said they worked 11-hour days, in violation of local labour laws barring students from working more than 40 hours per week.
In a statement, Apple said: "During the course of a recent audit, we discovered instances of student interns working overtime at a supplier facility in China. We've confirmed the students worked voluntarily, were compensated and provided benefits, but they should not have been allowed to work overtime."
The iPhone is Apple's most critical product line, representing 55 per cent of revenue for the quarter ended September 30.
Apple said demand for the iPhone X, which began shipping this month, was "off the charts" but according to several reports it was forced to cut the expected number of units produced in 2017 by as much as half. The iPhone X, starting at $US1000 ($A1400), is Apple's most expensive smartphone ever and has a nearly full edge-to-edge 5.8-inch screen, an advanced camera system, and a new facial-recognition feature used to unlock the device.
Apple and its suppliers have come under fire multiple times in past years for mistreatment of workers at Chinese manufacturing facilities, with reports of overcrowded factory dorms and excessive labour hours.