The report, Race to the Bottom, from the charity War on Want who are members of the Playfair 2012 campaign, found factories in Bangladesh supplying Adidas gave their lowest-paid employees less than the statutory minimum wage. The basic wage for the lowest-paid staff in the Adidas factories was just 9p an hour.

Exhausting working hours and severe abuse of workers were also found there. In one factory making baseball caps for Adidas one in five employees interviewed worked over 90 hours a week and two in three had clocked up more than 40 hours’ overtime in the previous month. At the same factory four in five of the staff had been verbally abused by their managers, two in five had been pushed by their managers and half had been publicly humiliated. Women workers from many of the factories described sexual harassment as widespread.

The report also surveyed workers making goods for Nike and Puma, who have both invested in high profile sponsorship deals with athletes competing in the London 2012 Games. Two thirds of the workers interviewed worked over 60 hours a week, in breach of Bangladeshi law, to earn enough money to cover the cost of basic essentials. Most of the workers lived in a single room with their families, sharing a kitchen and toilet with their neighbours.

Rahima Khatun, 21, who works as a sewing machine operator at one Adidas factory, said: “I had my first child last year, but I can’t spend enough time with her as I have to be work at the factory 12 hours a day, seven days a week. I have no choice, working overtime is compulsory. My managers are constantly swearing at us and pushing us if we don’t work fast enough. Sometimes the factory does not even pay us for three months at a time.”