Shanghai's Qingpu Prison, the Chinese prison at the centre of a forced labour scandal, describes itself as a "first-class" facility, where inmates can learn about jade sculptures and receive therapy.
But the jail, which detains both Chinese and foreigners, is now embroiled in a labour outcry after a purported secret message was sent in a Christmas card and discovered by a London schoolgirl.
The Sunday Times newspaper reported at the weekend that a six-year-old called Florence opened a card from a Tesco's supermarket in the UK to find a message inside, claiming to be from inmates in China.
"We are foreign prisoners in Shanghai Qingpu prison China," the message read in capital letters, inside a charity card featuring a kitten in a Santa hat.
"Forced to work against our will. Please help us and notify human rights organisation."
On its website, Qingpu Prison says holding foreign inmates from 40 nationalities "offers a lawful platform for cultural exchange."
The centre, on a 20 square kilometre (8 square mile) site, is staffed with more than 500 police officers across three units -- the logistics unit, foreign inmates unit and a maximum security unit.
The website shows several modern buildings, one with a glass facade, behind a green lawn and a blue sky and says it offers inmates "lessons on general law, morals, culture, skills and other basic education"
Qingpu prison says the prison comprises 51 psychotherapists and "a batch of invaluable cultural relics including bamboo and jade sculptures and embroidery, with the aim of nurturing the sentiments of the inmates in order to rectify the behaviours".
Released inmates have become "handicraft masters" in jade sculpture, it says.
But this is stark contrast to what former inmates say of their experiences in China's notoriously opaque prison system.
The secret message-writer asked the Christmas card receiver to contact Peter Humphrey, a former journalist who was imprisoned in China for 23 months -- nine months at Qingpu prison -- before being released in 2015.
Florence's father contacted Humphrey, who then took the story to the Sunday Times.
Humphrey wrote in the newspaper that he was jailed on "bogus charges that were never heard in court", and said the note-writers were certainly "Qingpu prisoners who knew me before my release."
He said he contacted fellow ex-prisoners after being contacted by the girl's family.
One of them said that for at least two years inmates in the foreign prisoner unit had picked designs and then packaged the Tesco cards, sealing the boxes and putting them into shipping cartons.
Writing in the Financial Times in February last year, Humphrey described the prison as "a business, doing manufacturing jobs for companies."
He said he was kept in a cell with 12 other prisoners, where they slept on iron bunks with the ceiling light always on and barred windows constantly open.
Inmates had to buy their own toiletries and necessities through the prison shopping system, he said.