The investigation by New York-based China Labor Watch (CLW) found a series of problems including inadequate worker training and overtime pay, excessive overtime hours beyond the limits set by Chinese law, and verbal abuse of workers by management.

"All workers are subject to long hours and low wages," the report said, noting that workers at Foxconn's plant in the central China city of Hengyang made an average of only $2.26 (€1.91) per hour.

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The 94-page report was unveiled on Monday and follows a nine-month investigation carried out by an undercover CLW investigator who was hired by the electronics manufacturing giant. The investigator worked on the factory's night shift, brushing dust off Alexa Echo Dot speakers from 8 p.m. until the small hours of the morning.

"After 6 a.m., I fell asleep on the assembly line," the investigator wrote, adding that workers needed permission to leave their chairs for the bathroom. When the shift finished, workers retreated to dormitories crowded with six bunks, the report said.

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Taiwan-based Foxconn, announced Monday that it had started an investigation into working conditions at its Hengyang factory, which mainly produces Kindles, tablets and Echo speakers for online retail giant Amazon.

"If any irregularities are found, we will immediately improve and correct them, and safeguard our company's corporate social responsibility," Foxconn said in a filing to the Taiwan stock exchange.

Dispatch workers' plight

Foxconn parts used in the gadgets of US tech giants like Apple, Microsoft, Intel and Amazon. The company has long faced allegations of poor treatment of its hundreds of thousands of employees in China.

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According to the CLW report, its employees continue to be subject to a grueling 100 hours of monthly overtime, which should have been no more than 36 hours. To dodge Chinese labor law, it uses middle-men labor companies to hire so-called dispatch workers, who make up 40 percent of Foxconn's workforce, but are not directly employed by the company.

Dispatch workers do not get sick pay or holiday pay and can be made redundant without wages during production slowdowns.

"As wages are low, workers must rely on overtime hours to earn enough to maintain a decent standard of living," the investigator was quoted as saying in the report.

In addition, workers didn't receive adequate safety training, and staff dormitories lacked fire extinguishers and escape routes. Staff was also subject to verbal abuse, it added.

Amazon 'concerned'

In response to the report, Amazon said it audited the factory in March and found overtime and use of dispatch workers were "issues of concern."

"We immediately requested a corrective action plan from Foxconn," Amazon said in a statement, adding that it was monitoring Foxconn's response and compliance with the company's Supplier Code of Conduct. "We are committed to ensuring that these issues are resolved."

In 2013, three Foxconn workers committed suicide at a Chinese factory. The company's "military management" was also blamed for 17 worker suicides in 2010.

uhe/jh (Reuters, AFP)