China Labor Watch (CLW), a non-profit organization monitoring working conditions in China, has released a report accusing toymaker Mattel (NASDAQ: MAT) of multiple labor violations in four Chinese factories.

The report, based on research at one directly owned Mattel factory and three supplier factories, was compiled after CLW investigators posed as factory production workers or conducted interviews. The group concluded Mattel was in violation of at least 15 labor rules, citing issues such as excessive overtime, low wages, multiple safety concerns, and lack of a grievance process.

The report cited overtime hours well in excess of the legal 36-hour monthly limit. CLW also claims that many of the labor violations have legal ramifications under Chinese wage laws.

In response to an inquiry from The Motley Fool, Mattel spokesman Alan Hilowitz stated: "At Mattel, we take the welfare of the people who make our products very seriously as evidenced by our long-standing commitment to our Global Manufacturing Principles (GMP), which also apply to vendor factories." He said Mattel is investigating the allegations.

Hilowitz also noted Mattel's participation in the ICTI and ICP toy industry trade groups, both responsible for monitoring business practice compliance.

Hilowitz said in a follow-up email that Mattel had found that one of the vendors that China Labor Watch named in the Mattel report has not been utilized by Mattel since 2009.

CLW said it is working with a French labor group, and other European partners, to require Mattel to address the alleged violations.

Tim Brugger has no positions in the stocks mentioned above. The Motley Fool owns shares of Mattel. Motley Fool newsletter services recommend Mattel. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.