25 June 2014 Last updated at 16:46 Share this page Continue reading the main storyRelated Stories Jump media playerMedia player help Out of media player. Press enter to return or tab to continue.Karen Wisínska said she found the note hidden in a pair of unworn trousersShe said it was only at that point she discovered the note and the prison identity card inside a pocket of the trousers.Mrs Wisínska said she knew it was some sort of plea for help because the letters SOS were written across the top, but she could not understand the rest of the writing.She posted the pictures of the items on Facebook, and when she received rough English translations of the note, she said she was "in shock" and "felt sick".She then contacted human rights campaigners at Amnesty International."I was shocked to find this note and card inside the trousers from Primark and even more shocked to discover that it appears to have been made under slave labour conditions in a Chinese prison," she said. 'Horrific'"I am only sorry that I did not discover the note when I first purchased the clothing - then I could have brought this scandal to light much earlier."Amnesty's Northern Ireland programme director, Patrick Corrigan said: "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," Mr Corrigan added.The note, translated into English, reads: "SOS! SOS! SOS! We are prisoners at a prison in Xiang Nan, Hunan, People's Republic of China."For a long time, we have been producing clothing for export. We work for 15 hours each day. What we eat is even worse than food for pigs and dogs. The work we do is similar to (the hard work) that oxen and horses do."We urge the international community to denounce China for this inhumane act," the note said. Primark said the trousers were last sold in Northern Ireland in October 2009A Primark spokesperson said the firm has started an" immediate, detailed investigation" and would be contacting Mrs Wisínska.