LONDON (Reuters) -Sony must face a mass lawsuit worth up to 6.3 billion pounds ($7.9 billion) over claims the PlayStation maker abused its dominant position leading to unfair prices for customers, a London tribunal ruled on Tuesday.

Sony Interactive Entertainment (SIE) was sued last year on behalf of nearly 9 million people in the United Kingdom who had bought digital games or add-on content through Sony's PlayStation Store.

Alex Neill, a consumer advocate who has worked on previous campaigns, is bringing the case against Sony which is valued at up to 5 billion pounds ($6.23 billion) plus interest.

Her lawyers said the aggregate damages estimate of the case was up to 6.3 billion pounds in court filings last month.

She says the company abused its dominant position by requiring digital games and add-ons to be bought and sold only via the PlayStation Store, which charges a 30% commission to developers and publishers.

The claim alleges customers have therefore paid higher prices for games and add-on content than they would have done.

Sony's lawyers argued the case was "flawed from start to finish" and said it should be thrown out.

The Competition Appeal Tribunal ruled that Neill's case could continue, though it said people who had made PlayStation Store purchases after the case was filed in 2022 should be removed from the proposed claimant class.

Neill said in a statement that Tuesday's ruling was "the first step in ensuring consumers get back what they're owed". Sony did not immediately respond to a request for comment.

($1 = 0.8025 pound)

(Reporting by Sam Tobin; Editing by Aurora Ellis and Jonathan Oatis)