Luxembourg’s data protection watchdog, the Commission Nationale pour la Protection des Données (CNPD), issued the fine in July.

The fine has only just come to light in a document filed by Amazon with the Securities and Exchange Commission (SEC) in the United States, which includes a list of legal proceedings involving the company.

The CNPD’s decision was based on a finding that “Amazon’s processing of personal data did not comply with the EU General Data Protection Regulation”, the document states, and imposed “a fine of €476 million and corresponding practice revisions”.

However, Amazon added: “We believe the CNPD’s decision to be without merit and intend to defend ourselves vigorously in this matter.”

A spokesperson for the company added: “There has been no data breach, and no customer data has been exposed to any third party. These facts are undisputed.”