T-shirts emblazoned with 'Girl Power' were made in a factory by impoverished female workers, often beaten and threatened with death, claims a new report.
According to an investigation by The Guardian, over 100 machinists at the factory in Bangladesh say they were recently sacked after protesting about their low wages.
Some employees earned around NZ$0.50c an hour, despite the Bangladeshi minimum wage recently increasing.
One female employee also claimed to have been beaten and threatened with death by management, after she spoke out to international outlets about the treatment.
The 'Girl Power' T-shirts came to international attention in January when UK television personality Holly Willoughby reposted a 2017 photo of herself and Spice Girl Emma Bunton wearing them on Instagram.
The Guardian reports neither Bunton nor Willoughby's management responded to requests for comment.
The T-shirts, which retail for around NZ$55, are sold online by 'F equals'; a clothing brand that says it is based on female empowerment.
In a 2017 essay penned for Mission.org, founder Danielle Newnahm wrote that F equals was "a new business for a new era".
"Female empowerment is squarely top of our agenda," she wrote in the company's mission statement.
The clothing company's website also states its clothing is made in a Fair Wear Foundation certified factory, "which means it is vetted for good working conditions and fair wages and by using organic cotton we drastically reduce the use of water".
In an apologetic response to the revelations, Newnham says the company outsourced garment manufacturing arrangements to international company Stanley/Stella.
"We have asked Stanley/Stella about these reported resignations - they have explained that this only happened recently and is being investigated by the Fair Wear Foundation and Stanley/Stella's country manager in Dhaka," Newnham wrote on the F Equals website.
"To clarify, we print our T-shirts here in the UK, but we are always concerned if anyone is treated badly - our entire mission is based on empowerment and if we receive evidence of poor treatment, we would look for another supplier immediately".
F equals says it chose Stanley/Stella because it had the "best credentials in terms of sustainability and good working conditions".