Google has been fined €2.95bn (£2.5bn) by the EU for allegedly abusing its power in the ad tech sector - the technology which determines which adverts should be placed online and where.
The European Commission said on Friday the tech giant had breached competition laws by favouring its own products for displaying online ads, to the detriment of rivals.
It comes amid increased scrutiny by regulators worldwide over the tech giant's empire in online search and advertising.
Google told the BBC the Commission's decision was wrong and it would appeal.
It imposes an unjustified fine and requires changes that will hurt thousands of European businesses by making it harder for them to make money, said Lee-Anne Mulholland, global head of regulatory affairs at Google.
There's nothing anti-competitive in providing services for ad buyers and sellers, and there are more alternatives to our services than ever before.
In its decision, the Commission accused Google of self-preferencing its own technology above others, intentionally boosting its own advertising exchange, AdX, over competing exchanges, which led to higher costs for competitors and publishers, impacting consumers.
The regulator has ordered the company to cease such practices and pay the nearly €3bn penalty.
Third Time Rules Broken
The Commission's fine is one of the largest it has handed to tech companies for breaching competition rules.
Teresa Ribera, executive vice president of the Commission, indicated the fine was higher due to prior violations. 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 said.
Ms. Ribera warned that Google has 60 days to outline changes or face imposed solutions. She suggested that a structural remedy, such as selling parts of its ad tech business, may be the only way for Google to eliminate its conflict of interest.
