Both firms have in the past made efforts to change their reputation for using sweatshop labour to make their products, and introduced a strict code of conduct for suppliers.
But a study by the American National Labor Committee showed that weekly shifts of more than 60 hours were the norm at producer Ocean Sky, Der Spiegel reported at the weekend.
There around 1,500 workers are watched by cameras as they labour in temperatures of around 37 degrees to sew football shirts for Puma and Adidas subsidiary Reebok.
Both Puma and Adidas have admitted having problems with Ocean Sky last year.
Maik Pflaum from the Christian initiative Romero has criticised them both for irresponsibility. Even ignoring the conditions under which the workers labour, a woman working there full time only earns around a quarter of what is needed to support a family, he said.
Trades unions in the region are traditionally weak and poverty levels high, factors used by the firms to their advantage. Ocean Sky has not responded to questions about its working conditions, while Adidas and Puma said they wanted to check conditions on the ground before commenting, the magazine said.