Google has been fined €1.49bn (£1.28bn) by the EU for breaching competition laws with its AdSense advertising service – its third such fine in as many years.
Announcing the new fine, the EU's competition commissioner Margrethe Vestager said Google had restricted rivals from appearing in online search advertisements.
Ms Vestager said the company had been fined for its "illegal practices in search advertising brokering to cement its dominant market position".
"They shouldn't do that – it denied consumers choice, innovative products and fair prices," added Ms Vestager.
In response, a Google spokesperson said the company had made a "wide range of changes" to address the commission's concerns.
The fine was issued because AdSense, one of Google's online advertising programs that allows websites to automatically serve targeted ads, was rigged to prevent rivals from appearing in those ads.
According to the competition investigation, Google had been including "exclusivity clauses" in its contracts with publishers since 2006.
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The third @Google case: @Google is fined €1,49bn for illegal practices in search advertising brokering to cement its dominant market position. They shouldnt do that – it denied consumers choice, innovative products and fair prices.
These were gradually replaced from 2009 with a different form of restriction known as a "premium placement" clause which prevented rivals' ads from being placed in the best advertising spots.
According to the commission, the fine follows its conclusion that "Google is dominant in the market for online search advertising intermediation in the EEA since at least 2006" with more than 85% of market share over that period.
"Google has abused this market dominance by preventing rivals from competing in the online search advertising intermediation market," the commission added.
The fine is equal to 1.29% of Google's turnover in 2018, but the commission stated that Google is also liable to be sued in civil cases by rivals who were harmed by its illegal practices.
It is the third time that Google has been fined by the competition commissioner since 2017, taking the total amount to €8.23bn (£7bn).