Sportswear manufacturer Puma AG is looking into claims that it is subjecting workers to unfair conditions in some of the Chinese factories used to produce its goods.

The allegations, which have been made by US watchdog The National Labor Committee (NLC), say that some of the German company's production sites in China are sweatshops where employees work up to 16.5 hours a day, for as little as 31 US cents an hour.

A joint report issued this month by NLC and China Labor Watch claims that the workers suffer from "gruelling hours, pitifully low wages, exploitation, abuse and denial of their rights."

The report signals out the Taiwanese-owned PouChen Group plants in Gaobu Town, Dongguan, in China, with particular focus on the 'Pou Yuen Plant F' site.

It is alleged that the factory workers' wages amount to just 1.66 per cent of the sneakers' $70 retail price, with Puma's gross profit being $34.09 from each sale.

Charles Kernaghan, director of the National Labor Committee, said: "A worker in China makes enough $70 Puma sneakers in the first five days and two hours of work, before the first week is over, to pay for his or her salary for the entire year."

Puma said that it makes frequent checks on its sites, and is not aware of any truth behind the claims.

It said its code of conduct specifies a "relevant legal minimum wage", and that working hours are restricted to 60 hours a week, including overtime.

The company added: "We are, however, certainly investigating all allegations".

Puma recently reported a 17 per cent rise in second-quarter sales, to €352.2 million.