Apple is in the spotlight again over working conditions for the people who make its products, following a BBC investigation that alleges poor treatment of workers in Chinese factories.

Undercover filming by the BBC investigative program Panorama showed exhausted employees who said they had worked 12 to 16 hours a day with no days off for long stretches.

They lived 12 to a room in dormitories and were forced to attend before and after work meetings without being paid for their time, the BBC said.

The BBC program alleges Apple is not living up to its promise to customers to improve working conditions in China.

Apple responded to the allegations with an internal memo in which Apple executive Jeff Williams and CEO Tim Cook said they were "deeply offended by the suggestion that Apple would break a promise to the workers in our supply chain."

Apple promised to improve conditions in its Chinese factories in 2010, after poor conditions were exposed following 14 suicides by workers at its Foxconn supplier in China.

Apple published a set of standards at the time for treatment of its factory workers and shifted some of its production to another factory, Pegatron, outside of Shanghai.

Long shifts, tired workers

The BBC’s investigation focused on the Pegatron employees, filming workers falling asleep while on their 12-hour shifts.

Panorama also investigated Apple’s claim that its materials are ethically sourced. It found some of the tin in Apple’s products came from illegal mines in Indonesia, where child labour was used to dig tin ore by hand in dangerous conditions.

Apple denied that it has broken its promise to improve working conditions and source materials ethically.

In the internal memo, Apple said the company regularly audits operations in China and has a team of experts there to ensure compliance with its supplier code of conduct.

"Sometimes critics point to the discovery of problems as evidence that the process isn't working," the memo read.

Apple audit system

"The reality is that we find violations in every audit we have ever performed, no matter how sophisticated the company we're auditing. We find problems, we drive improvement, and then we raise the bar."

The memo said work weeks of more than 70 hours were common several years ago, but Apple now has a standard of less than 60 hours a week for its suppliers.

The company claimed it is also addressing illegal tin mining by spearheading an Indonesian tin working group with other technology companies that holds smelters accountable for where tin is sourced and how it is mined.

Apple said it resents Panorama’s suggestion that it is not living up to its promise to customers to improve working conditions.

"We know of no other company doing as much as Apple does to ensure fair and safe working conditions, to discover and investigate problems, to fix and follow through when issues arise, and to provide transparency into the operations of our suppliers," Apple said.

Exposé unlikely to hurt sales

Scott Stratten, a marketing expert and author of Unselling, said he doesn’t believe Apple didn’t know about the violations.

The company makes its products overseas to keep prices down and knows the problems of operating in those markets, he told CBC News.

But he doesn’t think any tarnish created by reporting Apple’s human rights record will hurt the company.

“What’s going to happen — people are going to get angry right now. Then Boxing Day will happen. Do you think anybody’s going to care what happens to some poor worker overseas when they’re trying to get $50 off a flat screen or an iPad?” Stratten said.

“It’s a sad commentary. I wish it mattered to people, I really do.”

CBC's The Passionate Eye has the North American premiere of Apple's Broken Promises, Sunday, January 18 at 10 p.m. ET/PT on CBC News Network.