‘It’s like Citibank owning the Stock Exchange’

‘lock in’ companies, rather than let them use cheaper rivals.

It alleges Google engineers online advertising auctions to win 80 per cent of the business on offer.

The group behind the legal action said one Google employee had conceded that an ‘exchange shouldn’t be an immensely profitable business’ and that Google employees had explained the company charged high prices because ‘we can... smaller publishers don’t have alternative revenue sources.’

Google has disputed the allegations. Kent Walker, Google’s senior vice president, said in a blog post that the tech giant’s services ‘help people, create more choice, and support thousands of jobs’.

In Britain, the markets watchdog has said Google controls 90 per cent of the £7.3billion market for adverts. The Competition and Markets Authority has said Google’s ‘unassailable’ position inflates advertising prices, with costs passed on to consumers.