Image copyright Stephanie Wilson

A woman has revealed to US media how she found a plea for help from a man imprisoned in China in a bag from the upmarket Saks store in New York.

In the note, the man said he was forced to work 13-hour days at a Chinese prison factory to make the bags.

The discovery by Stephanie Wilson in September 2012 prompted a search for the man's whereabouts, reports say.

News website DNAinfo says it managed to track down the man - a Cameroonian who had already been released.

The high-end department store, Saks, said it had launched an investigation into the discovery but could not determine the specific origins of the bag, the report adds.

'Like slaves'

The 28-year-old woman made the discovery after pulling out a receipt from a paper shopping bag from the Fifth Avenue store.

The note, signed by Tohnain Emmanuel Njong, said: "We are ill-treated and work like slaves for 13 hours every day producing these bags in bulk in the prison factory."

He ended his letter by saying "thanks and sorry to bother you" and left an email address, which was discovered at the time to be defunct.

A passport-sized photo of a man in an orange jacket was also enclosed.

"I read the letter and I just shook," Ms Wilson told DNAinfo.

Ms Wilson, an Australian currently working in New York, passed the note on to the human rights Laogai Research Foundation.

The organisation was unable to track him down but raised awareness of the letter with the Department of Homeland Security and the Saks Fifth Avenue store.

With the help of social media accounts, DNAinfo said it recently made contact with someone who indentified himself as the man behind the letter.

"Unprompted, Njong described obscure details in the letter, like its mention of Samuel Eto'o, a professional soccer player on English Premier league team Chelsea, who like Njong is from Cameroon in West Africa," the website said.

According to DNAinfo, he was detained in the eastern Chinese city of Qingdao after being arrested for fraud in May 2011 - charges he denies.

He told the news website that he had worked long hours in the factory to produce paper bags, electronic goods and garments, from 06:00 until 22:00.

The 34-year-old said he wrote a total of five letters in both French and English calling for help.

"Maybe this bag could go somewhere and they find this letter and they can let my family know or anybody [know] that I am in prison," he added.

Mr Njong said he was released on a reduced sentence for good behaviour in December 2013 and was later reunited with his family in Cameroon, the website added.