Cupertino, Calif.-based tech giant Apple could be in trouble anew after BBC aired a report showing sweatshop conditions in Chinese factories that manufacture gadgets for Apple.

To do that, BBC used undercover reporters to secretly film the factories that produce the iPhone 6. Among the findings of the BBC expose are the employees work very long hours, the factories did not follow benchmarks on the issuance of ID cards, sleeping quarters, work meetings and underage workers.

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Because of their long shifts that last as long as 12 hours, many very tired workers at the Pegatron factories located outside of Shanghai fell asleep, the secretly taken video shows.

But it wasn't just the footage of exhausted workers that provide strong evidence of alleged abuses. An undercover BBC reporter who worked in a factory that makes parts for Apple computers worked 18 straight days even if he asked for a day off. Another reporter said by the time he ended his 16-hour shift, he was dead tired upon his return to the workers' dormitory.

He said, quoted by BBC, "Even if I was hungry I wouldn't want to get up to eat. I just want to lie down and rest. I was unable to sleep at night because of the stress."

Apple, in a statement, said it strives to ensure that fair and safe working conditions are the norm at Chinese factories it has contracted to make Apple products or parts. The company added it continues to work with its suppliers to address the deficiencies.

It said that based on its own monitoring, the average work hours of more than one million employees at Pegatron was 55 hours a week, which would still translate into 11 hours for a 5-day work-week or more than 9 hours for a 6-day work-week.

Global attention was focused on working conditions of Chinese factories that make Apple products or parts in 2010 when 14 employees committed suicide at Foxconn, the largest supplier of Apple.