LONDON - Google parent Alphabet must face a mass lawsuit which accuses it of abusing its dominance in the online advertising market, London's Competition Appeal Tribunal (CAT) ruled on Wednesday.

The lawsuit, which seeks damages of up to 13.6 billion pounds ($17.4 billion) on behalf of publishers of websites and apps based in the United Kingdom, is the latest case to focus on the search giant's business practices.

Ad Tech Collective Action is bringing the claim on behalf of publishers who say they have suffered losses due to Google's allegedly anticompetitive behaviour.

Google last month urged the CAT to block the case, which it argued was incoherent. The company "strongly rejects the underlying allegations", its lawyers said in court documents.

The CAT said in a written ruling that it would certify the case to proceed towards a trial.

Ad Tech Collective Action's lawsuit is just the latest against a tech giant at the CAT, which already this year has certified a $3.8 billion case against Facebook parent Meta and a nearly $1 billion case against Apple.

  - Reuters