The students, aged 17 to 19, said they were told that a three-month stint at the factory was required "work experience" that they had to complete in order to graduate.
Students have been employed illegally by Apple's main supplier in Asia in a bid to help the Cupertino-headquartered company deal with demand for new iPhone X, according to a report in The Financial Times. The student also claimed to have assembled up to 1,200 iPhone X cameras a day. Because the workers are classed as students, the overtime is illegal.
Apple confirmed that an audit revealed illegal overtime by student interns, but denied that they were forced to participate.
The school, together with the plant violated the law of China, as all interns must not work more than 40 hours a week.
According to the Financial Times, students working at the Foxconn plant, as part of a three month "work experience" placement, were routinely working 11-hour days assembling the newest phone, breaking Chinese overtime laws in the process. But the company did acknowledge that a "number of cases where portions of our campuses have not adhered to this policy" and that it has taken steps to prevent this from happening again. The six students were all working at Foxconn on internships. The student, who is training to be a train attendant at the Zhengzhou Urban Rail Transit School, said that the work had nothing to do with her studies.
Foxconn and Apple were not immediately available for comment when contacted by CNBC Tuesday.
It's usual for Foxconn to take on temporary workers in peak iPhone season, including students, but the FT reports that more seasonal workers than usual were recruited as Foxconn tried to make up for lost time on iPhone X production.
While Apple reportedly still faces supply shortage for the iPhone X, wait times for pre-ordered iPhone X have dropped from 5 to 6 weeks, at most, to 2 to 3 weeks.
All of the work conducted was voluntary, "and compensated appropriately", Foxconn said. Apple is expected to boost its iPhone X production up to 45 percent, according to noted Apple analyst Ming-Chi Kuo.