SEARCH engine Google has illegally exploited its dominance to squash competition and stifle innovation, a US judge has ruled.

The tech giant intends to appeal the ruling in a case brought by the US Justice Department, and any penalties or changes to its business would be demanded in a new legal phase of the anti-trust process beginning now. But “Google’s loss in its search anti-trust trial could be a huge deal, depending on the remedy,” Emarketer senior analyst Evelyn Mitchell-Wolf believes.

US District Judge Amit Mehta reviewed evidence including from executives from tech giants Google, Microsoft and Apple, declaring: “Google is a monopolist, and it has acted as one to maintain its monopoly.”

He cited Google’s dominance in the US — where it “enjoys an 89.2 per cent share of the market for general search services, which increases to 94.9 per cent on mobile devices” — as evidence of its monopoly position.

Lawyers for Google’s parent company Alphabet argued its success was down to its quality and consumer preference.

But the Justice Department’s case was that it has methodically thwarted competition to establish market dominance bringing in advertising revenues of $240 billion (£190bn) last year, and has spent money on agreements to install its search engine as the default option on mobile phones and other gadgets.

Where Microsoft’s search engine Bing was the default — as on Microsoft Edge products — it had a much larger user share, the court heard, concluding that the default settings are significant.

“This victory against Google is an historic win for the American people,” said Attorney General Merrick Garland. “No company — no matter how large or influential — is above the law.”

Penalties could include barring Google from installing such default agreements, but the appeals process will take five years.