Alphabet unit Google will face damages claims for up to 25 billion euros ($25.4 billion) over its digital advertising practices in two suits to be filed in British and Dutch courts in the coming weeks by a law firm on behalf of publishers.
Google's adtech has recently drawn scrutiny from antitrust regulators following complaints from publishers.
The French competition watchdog imposed a 220-million-euro fine on the company last year while the European Commission and its UK peer are investigating whether Google's adtech business gives it an unfair advantage over rivals and advertisers.
"It is time that Google owns up to its responsibilities and pays back the damages it has caused to this important industry. That is why today we are announcing these actions across two jurisdictions to obtain compensation for EU and UK publishers," Damien Geradin at law firm Geradin Partners said in a statement on Tuesday.
Google criticised the imminent lawsuits, saying that it works constructively with publishers across Europe.
"This lawsuit is speculative and opportunistic. When we receive the complaint, we'll fight it vigorously," a spokesperson said.
The British claim at the UK Competition Appeal Tribunal will seek to recover compensation for all owners of websites carrying banner advertising, including traditional publishers. Britain has an opt-out regime.
The Dutch claim is open to publishers affected by Google's actions. Litigation funder Harbour is funding both lawsuits.