Apple has found 91 children working at its supplier factories, according to its supplier responsibility report.
The report was based on 127 audits of factories last year.
Out of those 127, Apple said it found nine Chinese factories with 49 workers who were under 16, the local minimum working age.
A tenth factory, also in China, had employed 42 children under 16. "We determined management had chosen to overlook the issue and was not committed to addressing the problem," Apple said in the report.
Of the 127 factories audited:
- 60 percent had workers doing more than the 60-hour a week limit
- 64 percent didn't have clear emergency exits
- 63 percent didn't store hazardous chemicals properly
Apple had the supplier company send the young workers back to school, and then stopped doing business with it.
"Based on the poor likelihood of improvement, we terminated business with the facility," the report said, adding that it reported a school that helped recruit the children to the Chinese Government.
The report also highlighted 18 factories that charged excessive fees to recruit foreign workers, leaving them essentially in debt to their employer - which the firm calls "involuntary labour". Apple said it has forced the suppliers to pay back $3.4 million in such fees since 2008.
Furthermore, Apple revealed 137 workers at a Wintek factory were poisoned by a chemical called n-hexane, which was used to clean device screens. The chemical has since been removed from use.
While actually publishing such a report is unusual, critics noted that Apple didn't reveal the names of the suppliers causing trouble - despite the likelihood that those factories are still being used by other tech firms.
"I regard this report as a means of image-building rather than ensuring compliance with labour rights," Debby Chan of Hong Kong's Students and Scholars Against Corporate Misbehaviour campaign, told The Guardian.
Foxconn "saved lives"
Last year, a spate of suicides at the Shenzhen-based Foxconn factory drew attention to working conditions at the Apple supplier.
To find out more, Apple sent a team including COO Tim Cook in June, surveying 1,000 employees and investigating the suicides. The resulting report praised Foxconn for hiring counsellors, creating a 24-hour help centre, and installing "large nets" to catch "impulsive suicides".
"Most important, the investigation found that Foxconn's response had definitely saved lives," Apple's report claimed.