Apple is investigating fresh allegations of poor working conditions at a Chinese factory said to be producing a cheaper iPhone, expected to be unveiled next week.
It comes after China Labor Watch, a New York-based campaign group, said in a report that its investigations at Jabil Circuit's factory in Wuxi found employees working more than the 60-hour maximum working week that Apple requires of its suppliers. It also found employees were forced to work overtime.
"Workers at Jabil stand for 11 and a half hours of work per day, accumulating more than 100 overtime hours per month, three times that permissible by Chinese legal limits," CLW said. A YouTube video accompanying the report shows images of grimy dormitories where workers sleep on basic metal bunks.
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The timing of the report is awkward for Apple, which is preparing to unveil its new iPhones at events in California and Beijing next week.
Apple admitted that its own audits had found that Jabil sometimes fell short of its code of conduct.
"An audit completed earlier this year did find that some employees had worked more than six consecutive days without a day of rest, and Jabil has been working with our team to better manage overtime," Apple said in a statement.
"Year to date, Jabil Wuxi has performed above our 92 per cent average for compliance with Apple's 60-hour per week limit ... Jabil has a proactive auditing program of their own and they have an excellent track record of meeting Apple's high standards."
Jabil said it is "committed to ensuring every employee is provided a safe working environment where they are treated fairly, with dignity and respect. We take seriously any allegation that we are not fulfilling that commitment and are taking immediate action to ensure recent allegations are thoroughly investigated and, if found to be credible, corrected."
It said it had already begun "corrective action" about some of the issues flagged in CLW's report after uncovering them in its own audits, and said a team would investigate the new claims.
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Apple's most recent supplier transparency report, which provides a more detailed account of working conditions than its rivals in the consumer electronics industry, found 99 per cent compliance with a 60-hour work week in June. However, that figure dipped to 88 per cent last September, as the company geared up for the launch of new iPhones, iPads, Macs and iPods.
CLW has been a frequent critic of Apple's supply chain conditions but its latest allegations are not as severe as some problems that Apple suppliers such as Foxconn have faced in previous years.
CLW has also accused Samsung and Apple supplier Pegatron of violating workers' rights over the past year.