Apple is looking into claims that its supply chain uses illegal student labor in the production of its Apple Watch, according to reports.

A human rights group claims Quanta Computer, a Taiwanese Apple supplier, employed students illegally and required them to work overnight and overtime shifts and allowed only one day off per week. Sacom, the human rights group that brought forward the claims, says that Quanta is the exclusive manufacturer of the Series 1, 2 and 4 Apple Watch, and a primary manufacturer of the Series 3.

Sacom interviewed a number of high school students in the preparation of its report. Apple has provided a statement to the Financial Times, but has remained silent besides that.