The tech giant is accused of making agreements with mobile device manufacturers to make Google Search the default search engine on devices, which has pushed prices up for UK advertisers.

Roger Kaye KC, a former deputy High Court judge, is leading the claim which has been filed at the Competition Appeal Tribunal (CAT). It states that Google’s conduct has affected between 500,000 and 1.5 million UK advertisers, resulting in “excessive and unfair prices” for advertising.

The claim seeks compensation for all advertisers who paid Google for search advertising between January 2011 and the present – with the estimated award being £25bn.

Mr Kaye said: “Monopolising the advertising space to the point of abuse cannot continue.”

Duncan Hedar, head of competition at KP Law, said: “In contrast to previous cases filed in the UK, Mr Kaye KC seeks to take the action one step further by rightly compensating the vast number of businesses who’ve had to suffer the imposition of Google’s abuse of power.”

A Google spokesperson said: “These types of meritless claims are brought by lawyers seeking profit and bring little-to-no benefit to those they represent.”