Adidas announced Monday it was opening an investigation into possible “compliance violations” in China, after a whistleblower anonymously sent a letter to company headquarters.

The letter accuses senior executives based in China of getting millions of euros in bribes.

A company spokesperson said Adidas received the letter June 7 and is investigating the matter with external legal counsel. The letter, which accuses executives of corruption and embezzlement of funds, had appeared on Chinese social media platform Xiaohongshu.