【Peggy Markoff】

Apple has confirmed with Mashablethat some high school interns at the iPhone-producing Foxconn plant in China worked overtime to produce iPhones.

The Peggy Markoffcircumstance became public when six students from Zhengzhou Urban Rail Transit School told the Financial Timesthey were "forced" to work at the facility to complete internship requirements. One student reported assembling 1,200 phones in a single day.

In a statement, an Apple spokesperson acknowledged the students should not have been working overtime to assemble Apple's latest, gleaming handsets. The students said they worked up to 11 hours a day.

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.

Apple noted that interns, while working at the Foxconn plant — which can produce up to half a million iPhones in a single day — are not a significant part of the iPhone-assembling workforce.

At this facility, student intern programs are short term and account for a very small percentage of the workforce. When we found that some students were allowed to work overtime, we took prompt action.

The tech giant says they have "specialists" on-hand to "ensure the appropriate standards are adhered to." Yet, at a sprawling 2.2-mile square facility which employs up to 350,000 workers, it seems some oversight can occur.

We know our work is never done and we’ll continue to do all we can to make a positive impact and protect workers in our supply chain.

But for those Chinese workers that aren't students, working overtime at some Chinese factories is mandatory. In 2016, a graduate student at NYU, Dejian Zeng, went undercover at a Pegatron iPhone producing factory, and told Mashableabout the experience. Like Foxconn, Pegatron is an electronics manufacturing giant.

Zeng said he worked 12 hours a day screwing "1,800 screws into 1,800 iPhones" six days a week. He made the equivalent of around $450 a month, even when working overtime.

“What shocks me is that overtime is involuntary," Zeng said. “[The workers] are actually kind of forced to do overtime.”