The European Commission has announced the company had breached competition law by favouring its own products for placing online ads, to the detriment of its rivals.

The regulator said the practice inflated costs for competitors and publishers, while reducing their revenues.

In a statement to the BBC, Google’s global head of regulatory affairs, Lee-Anne Mulholland, said: “It imposes an unjustified fine and requires changes that will hurt thousands of European businesses by making it harder for them to make money.

“There’s nothing anti-competitive in providing services for ad buyers and sellers, and there are more alternatives to our services than ever before.”

The European Commission said Google had engaged in “self-preferencing” by boosting its advertising exchange, AdX, above competitors.

It found the company had deliberately given preference to its own ad-buying tools over exchanges where adverts are sold in real time.

The regulator ordered the company to stop the practice and pay the fine, one of the largest it has issued in a competition case.

US president Donald Trump, 79, criticised the decision in a post on social media.

He said it was “very unfair” and threatened to launch an investigation into European technology practices that could lead to tariffs.

He wrote: “As I have said before, my Administration will NOT allow these discriminatory actions to stand. The European Union must stop this practice against American Companies, IMMEDIATELY!”

Trump has repeatedly attacked European fines against US tech firms, though the American government has also pursued lawsuits against Google over its alleged monopoly in online advertising.

In its ruling, the European Commission said Google’s practices had distorted competition, leaving consumers exposed to higher costs as publishers passed on lost revenues.

Teresa Ribera, executive vice president of the Commission, said: “In line with our usual practice, we increased Google’s fine since this is the third time Google breaks the rules of the game.”

She added: “At this stage, it appears the only way for Google to end its conflict of interest effectively is with a structural remedy, such as selling some part of its ad tech business.”

In 2018, the Commission fined Google £3.9billion for using its Android operating system to cement its dominance in the mobile market.