Retailers announced on Thursday their plans to file a £1 billion ($1.3 billion) class action against Amazon in London, accusing the tech giant of illegally misusing their data to enhance its sales and profits.

The British Independent Retailers Association (BIRA) is spearheading the claim, alleging that Amazon exploited data belonging to U.K. retailers and manipulated its "Buy Box" feature to redirect revenue and profits from these retailers to itself. The "Buy Box" prominently features the "buy now" and "add to cart" buttons on Amazon’s website, influencing purchasing decisions.

According to BIRA, Amazon’s actions date back to October 2015. The association contends that the online retail giant used confidential, commercially valuable information to guide decisions on introducing new products, designing them, and bringing them to market. This, coupled with the "Buy Box" manipulation, enabled Amazon to enter markets and siphon profits from U.K. retailers.

Amazon has yet to respond to requests for comment on the allegations.

Andrew Goodacre, BIRA's chief executive, stated that the filing marks the "first step" towards compensating retailers for Amazon's alleged misconduct. He expressed confidence that the Competition Appeal Tribunal would authorize the claim to proceed and looked forward to presenting the case on behalf of U.K. retailers.

"This is a watershed moment for U.K. retailers, especially for small independent retailers in this country," Goodacre added.

Boris Bronfentrinker, a partner at BIRA's law firm, Willkie Farr & Gallagher (UK) LLP, emphasized that the collective action aligns perfectly with the collective action regime designed to handle such claims.

"No individual retailer, no matter how large, is willing to get into the lion's den and take the fight to Amazon. But, fortunately, BIRA has shown that it will stand up and fight for U.K. retailers," Bronfentrinker said. "Retailers in the U.K. were entitled to be treated better and fairly by Amazon."

The British Independent Retailers Association is represented by Sarah Ford KC of Brick Court Chambers and Jason Pobjoy of Blackstone Chambers, instructed by Boris Bronfentrinker, Elaine Whiteford, and Michelle Clark of Willkie Farr & Gallagher (UK) LLP. The claim is funded by Litigation Capital Management.

This class action in London is not Amazon’s only legal challenge. The tech company is also facing a proposed class action in Washington federal court, which alleges that "hundreds of millions" of customers have overpaid for items due to Amazon rigging algorithms to favor its own retailers and third-party sellers using its fulfillment service.