A women's rights charity is investigating claims that a promotional T-shirt worn by several senior U.K. political leaders to promote feminism was produced in a sweatshop.

The charges made by the Mail on Sunday allege that garment workers in Mauritius made the T-shirt emblazoned with the words "This is what a feminist looks like." The newspaper says the women who work in the Indian Ocean island factory sleep 16 to a room and make 62 pence ($1) an hour.

Eva Neitzert, deputy CEO of the Fawcett Society, said it had been assured the T-shirts were produced ethically and will ask fashion retailer Whistles to withdraw the range if evidence of mistreatment emerges.

The 45-pound ($71) T-shirt was produced in collaboration with ELLE magazine for a December issue on feminism.