Beijing has dismissed accusations of forced labour at a Shanghai prison, a day after media reports about a message found in a Christmas card saying it had been packed by inmates.

Key points: Zhejiang Yunguang Printing denied what it referred to as "unfounded claims"

Zhejiang Yunguang Printing denied what it referred to as "unfounded claims" Mr Humphrey said he had never met the family who found the message

Mr Humphrey said he had never met the family who found the message In 2014, a Northern Ireland shopper said she found a note wrapped around a Chinese prison ID inside trousers she bought

A six-year-old girl in London discovered the apparent plea for help written inside the Christmas card, which was made by the company Zhejiang Yunguang Printing and sold at the supermarket chain Tesco.

"We are foreign prisoners in Shanghai Qingpu Prison China. Forced to work against our will," the note said.

The message urged whoever received it to contact Peter Humphrey, a British former journalist and corporate fraud investigator who was imprisoned in the same jail from 2014-2015.

The family contacted Mr Humphrey, who then wrote the story for The Sunday Times.

The author of the note asked whoever found it to contact human rights organisations. ( Reuters )

China's Foreign Ministry spokesman Geng Shuang told a press briefing last night the story was "just a drama choreographed by Mr Peter Humphrey", a claim Mr Humphrey has denied.

"I can tell you that after verifying with relevant departments, we know for sure that there is no forced labour of foreign prisoners in Qingpu prison in Shanghai," the spokesman said.

Zhejiang Yunguang Printing also denied what it referred to as "unfounded claims" in an article published by Chinese state media Global Times.

"We only became aware of this when some foreign media contacted us. We have never done such a thing," the company was quoted as saying.

"Why did they include our company's name? Do they have any evidence that we have been working with any prison?"

China's Foreign Ministry spokesman said there was no forced labour in Qingpu prison. ( Reuters: Aly Song )

The company suggested the incident may be a politically motivated bid to smear China's human rights record.

"Are they trying to stir up a political thing? Are they trying to challenge our country's human rights?" the company said, adding it may have been a "manufactured" incident.

Companies investigate Chinese supplier

Mr Humphrey rejected to Chinese Government accusations the story was concocted, saying he had never met the family who found the card. ( Supplied )

Mr Humphrey responded to the Chinese Government's accusations by saying he had never previously met the family who found the card.

"I never had any possible way to fabricate anything at all in this incident and this story," Mr Humphrey said, adding the message fitted "with everything I know".

"I have spoken with ex-prisoners who were released this year and who confirmed that that prison unit was making packaging for Tesco Christmas cards."

Mr Humphrey spent 23 months in prison on charges of illegally obtaining private records of Chinese citizens and selling the information to clients including drugmaker GlaxoSmithKline.

Tesco suspended the Chinese supplier of the Christmas cards on Sunday and said it had launched an investigation.

The ABC revealed the Chinese company is also a supplier to Australia's Cotton On Group — a relationship the group is now investigating.

This is not the first time a shopper has come across a secret message about forced labour in China's prison system.

In June 2014, Northern Ireland shopper Karen Wisínska said she found a note wrapped around a Chinese prison ID located inside a pair of trousers she bought in Belfast.

The writer purported to be a prisoner in the Xiang Nan Prison in China's Hubei Province. ( Supplied: Amnesty International )

The writer said they were a prisoner in the Xiang Nan Prison in China's Hubei Province and forced to work 15 hours a day, according to Amnesty International.

"Our job inside the prison is to produce fashion clothes for export," the note said.

"We work 15 hours per day and the food we eat wouldn't even be given to dogs or pigs."

Patrick Corrigan, Northern Ireland program director of Amnesty International, urged UK companies to monitor their supply chains and "terminate contracts when they discover abuse".

"It is a horrific tale. It's very difficult to know whether it's genuine, but the fear has to be that this is just the tip of the iceberg," he said in the Amnesty report.

Amnesty has previously documented the use of forced labour in China's prison system, including in jails used to hold political prisoners.

ABC/Reuters