Google has suffered a big setback in its long-running legal battle with the European Union, with a top advisor to the EU’s highest court recommending that the tech giant’s appeal against a €4.12 billion (A$6.7 billion) antitrust fine be dismissed.

The ruling relates to allegations that Google abused its dominance of the Android mobile operating system by requiring phone manufacturers to pre-install Google Search and Chrome, giving the US company an unfair advantage.

The European Court of Justice will rule in the coming months, with an advisor backing the 2018 fine, which is an opinion the court usually follows.

The original fine of €4.34 billion was slightly reduced in 2022 after Google appealed to a lower EU court, but regulators still found the company had violated competition rules.

This case is one of three major EU antitrust actions against Google, which has now been fined more than €8 billion in Europe over the past decade.

Google responded to the latest development with disappointment, warning that the decision could “discourage investment in open platforms” and harm both users and developers.

However, the European Commission has remained firm in its crackdown on Big Tech dominance, strengthened by new enforcement powers under the Digital Markets Act.