Apple admits that high school students interning at Foxconn worked beyond their legal hours on the iPhone X production lines.

Must read: How strong are iPhone X sales?

Six high school students, who were part of 3,000 students taking part in a three-month-long work experience program, told the Financial Times that they routinely worked 11-hour days assembling iPhone X smartphones at Foxconn’s Zhengzhou plant in China.

This is illegal for student interns under Chinese law.

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.

One student claimed to assemble as many as 1,200 iPhone X handsets a day.

“We are being forced by our school to work here,” said Ms Yang, an 18-year-old student training to be a train attendant who declined to use her first name for fear of punishment. “The work has nothing to do with our studies.”

Apple has confirmed that the students worked illegal overtime, but deny claims that the students were forced.

We’ve confirmed the students worked voluntarily, were compensated and provided benefits, but they should not have been allowed to work overtime.

There have been repeated claims that iPhone X production had been dogged by delays and problems in the run up to the launch, and that manufacturing had been pushed as late as mid-October.

See also: