The “This is what a feminist looks like” t-shirt proudly worn by Harriet Harman during Prime Ministers Questions last Wednesday was made by factory girls in the Mauritius who earn just 62p an hour and sleep 16 to a room. The shirts are currently being sold at Whistles for £45 each, with all profits donated to the Fawcett Society, a campaigning group for women’s rights. But one worker told the Mail on Sunday “We don’t feel like feminists. We don’t feel equal. We feel trapped.”

The t-shirts are being promoted by women’s magazine Elle in their forthcoming edition, which features a number of men including Deputy Prime Minister Nick Clegg, Labour Leader Ed Miliband, and the actors Benedict Cumberbatch, Richard E Grant and Simon Pegg all sporting the shirt.

Prime Minister David Cameron landed himself in hot water by repeatedly refusing to take part in the feature by wearing one of the shirts, but it appears that he may have the last laugh as an investigation by the Mail on Sunday has revealed that the girls making the shirts are committed to 45 hour weeks for which they are paid just 6000 rupees – about £120 – a month, meaning that it would take them a week and a half to earn the money required to buy one of the shirts.

Hailing from India, Bangladesh, Vietnam and Sri Lanka, the girls sign a four year contract with Compagnie Mauricienne de Textile (CMT), the company which owns the factories, and are unable to see their families during that time. Most send their earnings home to their families, as the rupees are worth more in their native countries than they are in Mauritius. Whilst on-site they sleep 16 to a room and leaving the site during the working week is frowned upon in case they return “hung-over”.

Fayzal Ally Beegun, president of the International Textile, Garment and Leather Workers Union said: “The workers in this factory are treated very poorly and the fact that politicians in England are making a statement using these sweatshop T-shirts is appalling.

“It would take a woman working in the factory nearly two weeks just to buy one shirt. What is feminist about that? These women have nothing in this world. They are paid a pittance and any money they do receive they send back home.

“They work very long hours and have no lives other than their work. They are on four-year contracts that mean they don’t get to see their families in that time. What kind of existence is it when you are sharing your bedroom with 15 other women?

“The women have no careers or even the most basic of opportunities. This is not what feminism is supposed to be.”

CMT employs 13,000 staff in its factories, 4,500 of whom are migrant workers who live on site. Its annual turnover is £125million, earned by producing 40million t-shirts a year for retailers such as Topshop, Urban Outfitters and Next. The ‘feminism’ t-shirt cost just £9 to make.

The company was heavily criticised in 2007 when it was discovered that women were being paid just £4 a day to produce garments for Sir Philip Green’s Kate Moss collection at Topshop. It was also under fire for paying differing rates to workers of different nationalities and promising migrant better wages than they actually received, but since then the company has altered its policies, now paying the Mauritian minimum wage to all workers, regardless of nationality, and sets out the correct wages before the workers sign their contracts.

Francois Woo, managing director of CMT’s factory in La Tour Koenig, north Mauritius told the Mail: “The Mauritian government has set out a minimum wage that we must pay and we abide by their rules.

“I am like a parent to the workers. They are free to come and go as they please but if they go out on a weeknight I will not be happy because then they will turn up for work the next day hung-over. If people didn’t want to work for us then they don’t have to, nobody is forcing them. If they have the chance to earn more somewhere else then they should go elsewhere. If they didn’t like it, then we would not have existed as a company for 28 years.”

But the workers disagreed. One 30 year old migrant worker said: “I have worked here for four years and I have not been able to see my son or husband in Bangladesh during all that time. We work very hard, sometimes 12 hour days, for not much money. I send all my money home and could not afford to fly back and see my family.

“It is awful but we have no choice. In my country, the rupees I earn here are worth three times as much as they are in Mauritius.

“How can this T-shirt be a symbol of feminism?”

The Fawcett Society, who commissioned the shirts as part of their campaigning activities has said that it was “disappointed” to hear allegations that the shirts were produced in sweatshop conditions.

“As a charity that campaigns on women’s rights in the labour market, we take ethical standards very seriously. We have been assured by Whistles that the “This is what a feminist looks like” range has been produced to ethical standards,” said Dr Eva Neitzert, deputy chief executive at the Fawcett Society.

“We have been very disappointed to hear the allegations that conditions in the Mauritius factory may not adhere to the ethical standards that we, as the Fawcett Society, would require of any product that bears our name.

“If any concrete and verifiable evidence of mistreatment of the garment producers emerges, we will require Whistles to withdraw the range with immediate effect and donate part of the profits to an ethical trading campaigning body,” she said, adding that Whistles had assured the Fawcett Society that the factory was “a fully audited, socially and ethical compliant factory.”

A spokesman for Whistles, which counts the Duchess of Cambridge amongst its clients, said “CMT has Oekotex accreditation, [an independent certificate for the supply chain] which fully conforms to the highest standards in quality and environmental policy, while having world-class policies for sustainable development, social, ethical and environmental compliance.

“We carry out regular audits of our suppliers in line with our high corporate social responsibility standards”.

Upon the company’s launch, Jane Shepherdson, founder of Whistles intoned “Customers cannot keep buying cheap clothes and not ask where they come from” – as “someone somewhere down the line is paying”.

A Labour spokesman said: “This was a campaign run by Elle and the Fawcett Society to promote feminism and we were happy to support it,” whilst a spokesman for Nick Clegg said “Nick Clegg had no idea where these T-shirts were being made and can only assume that the Fawcett Society were unaware of the origins, or they would not have asked him to wear it. He remains entirely supportive of efforts to ensure all women are treated as equals in this country and the world over.”