Amazon.com appealed against a penalty worth $865 million for allegedly violating the European Union’s tough data protection rules.

According to Luxembourg court spokesman Henri Eippers, the appeal was filed at the Luxembourg Administrative Tribunal on Friday.

The challenge comes after CNPD, Luxembourg’s data protection regulator, where Amazon has its EU base, in July imposed the fine on the US company.

The regulator ruled that Amazon was in breach of the bloc’s General Data Protection Regulation (GDPR) through its processing of users’ personal data. The decision was prompted by a 2018 complaint from French privacy rights group La Quadrature du Net.

The world’s biggest online retailer has attracted scrutiny in recent years for the vast trove of data it has amassed on a range of customers and partners, including independent merchants who sell on its retail marketplace, users of its Alexa digital assistant, and shoppers whose browsing and buying history inform what Amazon shows them on its website.

Amazon declined to comment on the appeal, but referred to a previous statement in July that “there has been no data breach, and no customer data has been exposed to any third party”.

Amazon previously said it strongly disagreed with the Luxembourg authority’s findings.

The company says it collects data to improve the customer experience, and sets guidelines governing what employees can do with it. Some legislators and regulators have raised concerns that the company has used what it knows to give itself an unfair advantage in the marketplace.

EU data protection regulators’ powers have increased significantly since the bloc’s GDPR rules took effect in May 2018. The law allows watchdogs to levy fines of as much as 4 per cent of a company’s annual global sales.

The privacy inquiry adds to intense antitrust scrutiny of Amazon’s business in Europe. Amazon is being investigated by the EU over its use of data from sellers on its platform and whether it unfairly favours its own products. Germany has several investigations into Amazon’s sales. The UK is also examining similar issues to the EU.