LONDON — Chinese online retailer Temu is facing a European Union investigation over suspicions it failed to prevent the sale of illegal products, the 27-nation bloc's executive arm said on Thursday.

The European Commission opened its investigation five months after adding Temu to the list of 'very large online platforms' needing the strictest level of scrutiny under the bloc's Digital Services Act (DSA). It's a wide-ranging rule book designed to clean up online platforms and keep internet users safe, with the threat of hefty fines.