Amazon.com is being sued in the United Kingdom for up to £900 million ($1 billion) in damages over accusations that the online marketplace exploited its dominant position by favouring its own items over those of competitors.

Julie Hunter, a consumer rights campaigner, intends to file the group action on behalf of British consumers who’ve purchased items on Amazon since October 2016, according to attorneys representing her. The planned lawsuit, which Amazon has said is “without merit,” would be the latest collective action launched against a tech giant in the UK Competition Appeal Tribunal (CAT).

Buy Box

According to law firm Hausfeld, which represents Hunter, Amazon violated competition law by deploying “a clandestine and self-favouring algorithm” to push its own items through its website’s ‘Buy Box’ feature.

Hunter said that the Buy Box favours items offered by Amazon itself or sellers that pay Amazon to handle their logistics. According to Hunter, the feature is far from being a suggestion based on cost or quality. Competing vendors are essentially blocked out, no matter how strong their bids are.

An Amazon spokesperson said the claim is without merit, and the organization is sure the legal process will show that.

British antitrust action

The action comes after Britain’s antitrust agency announced in July that it’s examining Amazon for possible competition law violations, including how it chooses which goods appear in the Buy Box feature. Amazon has faced similar investigations overseas and recently proposed a settlement to the European Commission to avoid potentially crippling EU antitrust fines. The proposal wasn’t accepted, and the EU investigation is ongoing.

The platform has also refused to reveal its product-search technology to an Australian competition commission, which is increasingly concerned with large marketplace platforms favouring in-house items. In July, the UK Competition Appeal Tribunal (CAT) accepted a £920 million ($1.1 billion) damages claim against Google. In May, it approved another lawsuit for up to £1.7 billion against Apple.