More than a thousand Chinese college students were forced to manufacture the PlayStation 4 as part of an internship at a Foxconn factory, reports Dongfang Daily.

Xi'an Technological University students spent two months at the Foxconn plant in Yantai, China, for a work-study program that ran from August to this week. Students from the program told Dongfang Daily that the internship was mandatory — their diploma would be withheld if they didn't participate, and if they attempted to drop out of the program early, they would lose six credits' worth of courses. The students also said they were given tasks outside of their areas of study, and sometimes performed manual labor.

The same Foxconn plant came under fire last October when it was found to be using underage workers to manufacture the Wii U.

Foxconn said in a statement to Quartz that during an internal investigation, it found the students were given night shifts and forced to work overtime, a violation of company policy.

"Immediate actions have been taken to bring that campus into full compliance with our code and policies," said a Foxconn representative, including "reinforcing the policies of no overtime and no night shifts for student interns, even though such work is voluntary, and reminding all interns of their rights to terminate their participation in the program at any time."

In a statement given to MCV, Sony said that Foxconn complies with Sony's Supplier Code of Conduct, which the company established in 2005.

"The Sony Group established the 'Sony Supplier Code of Conduct' in June 2005 with the expectation of every supplier agreeing and adhering to the policies of the Sony Group in complying with all applicable laws, work ethics, labour conditions, and respect for human rights, environmental conservation and health & safety," said Sony. "We understand Foxconn fully comprehend and comply with this 'Sony Supplier Code of Conduct.'"

Correction: This article originally described the internship as unpaid, but the students were in fact paid the same as a normal Foxconn worker — 1,600 yuan (about $261.62) per month — according to the company and their school, Xi'an Technological University. We've edited the article above to reflect this, and apologize for the error.

[Thanks, Fan Zhang]