In a significant setback for Google, a US federal judge has ruled that the tech giant must face trial over allegations by antitrust enforcers that it has illegally monopolised the online advertising technology market.

At a hearing on Friday in Alexandria, Virginia, US District Judge Leonie Brinkema denied Google's motion to win the case without a trial. She stated there were "way too many facts in dispute" to grant summary judgement in Google's favour.

The ruling clears the way for the hotly anticipated trial to commence as scheduled on 9th September. Google had argued the antitrust laws do not prohibit companies refusing to deal with rivals and claimed regulators had failed to accurately define the relevant ad tech market.

However, Judge Brinkema was unconvinced by these arguments, determining that a trial was required to properly assess the complex matters at stake.

The US Department of Justice and a coalition of state attorneys general sued Alphabet's Google last year. They alleged the internet giant was unlawfully monopolising digital advertising, overcharging customers and stifling competition.

The lawsuit primarily seeks to force Google to divest its digital advertising business to allow greater competition in the market. Regulators have accused Google of controlling too many links in the ad tech supply chain.

In a further blow, Judge Brinkema granted the government's request to block a former FBI cybersecurity consultant for Google from testifying as an expert witness at trial.

A Google spokesperson said the company looks forward to "setting the record straight", while the Justice Department declined to comment.

This represents the latest major regulatory challenge facing Google's lucrative advertising business model, after it was hit with antitrust claims over its Search dominance.

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