Sarah Tew/CNET

Apple's main supplier in China used student workers illegally to manufacture parts for the newly launched iPhone X, the Financial Times reported Tuesday.

Six high school students said they regularly worked 11-hour days for Foxconn, a longtime manufacturing partner of Apple, at a factory in Zhengzhou. Students are classed as interns, making their overtime hours illegal under Chinese law, the Financial Times said.

One student reportedly assembled up to 1,200 iPhone X cameras a day.

Demand for the iPhone X is "off the charts," according to Apple, but supply problems have plagued the launch of the company's new superphone, which went on sale earlier this month. Manufacturers reportedly aren't building the 3D sensors for the phone's facial recognition camera technology fast enough to keep up with yield, forcing factories to bring on more workers

This is far from the first time Foxconn has come under scrutiny for its labor practices. Back in 2012, reports of riots, suicides and poor working conditions at Foxconn factories came to light, forcing Apple to ask the Fair Labor Association to step in and inspect factory conditions.

"Apple is dedicated to ensuring everyone in our supply chain is treated with the dignity and respect they deserve," an Apple spokesman said in a statement Tuesday. "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."

The allegations are doubly problematic for Foxconn as the students claimed they were being forced to work at the factory for three months of "work experience" in order to be allowed to graduate.

In total, 3,000 students aged 17 to 19 from the Zhengzhou Urban Rail Transit School were sent to work at the factory in September, according to the FT.

Apple and Foxconn both confirmed to the FT that students had been discovered working overtime and that they would be taking remedial action, but denied that the students were forced to work at the factory.

"We've confirmed the students worked voluntarily, were compensated and provided benefits, but they should not have been allowed to work overtime," an Apple spokesman told CNET. The company took prompt action when it discovered the problem, the spokesman said, adding that a team of specialists is now on site to ensure standards were adhered to.

A spokeswoman for Foxconn said in a statement that all student interns working at the company enter the program voluntarily and are fully informed of their rights, but that some company campuses were not following procedure.

"We have investigated all of these cases, and confirmed that while all work was voluntary and compensated appropriately, the interns did work overtime in violation of our policy," she said.

Foxconn has taken corrective action and will regularly review the internship program to ensure it complies with relevant policies and regulations, the spokeswoman said. "This will not be repeated."

Originally published Nov. 21, 5:02 a.m. PT.

Update, 6:47 a.m. PT: Added comments from Apple and Foxconn.

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