LONDON — Europe’s antitrust authorities have threatened to impose significant fines on Google’s operations on the Continent if the company does not give rivals greater prominence in some search results across the 28-member bloc.
The move — outlined in a so-called statement of objections that was sent to Google in April and on Thursday to a number of companies that have balked at Google’s activities here — is the latest step in the five-year antitrust case brought by European officials.
The details outlined in the letters explain for the first time the changes to Google services that investigators are demanding and how much the company could be fined.
The focus has centered on Google’s dominant position in Europe’s online search market, where it commands an approximately 90 percent market share, compared with about 65 percent in the United States. European officials contend that Google has used this position to unfairly favor some of its own services over those of rivals, including Microsoft and Yelp.
As part of the potential sanctions, Google may face fines based on the revenue generated from European users on the company’s AdWords online advertising service, according to two people with knowledge of the statement of objections, who spoke on the condition of anonymity because they were not authorized to talk publicly on the matter.
The financial penalties also may extend to fines linked to revenue from Google’s comparison shopping service in Europe and revenue from product queries on Google’s search engine in the region, the two people added.
Unlike in the United States, official antitrust charges in the European Union are typically not made public.
The 120-page document from European officials also threatened to force Google to use the same methods and processes to rank rival services as it does for its own online search products. Antitrust regulators said that the abuse dated to at least 2008, according to one person with knowledge of the matter who had reviewed the document.
Many rivals have complained that Google favors its own search services, particularly so-called vertical searches that are based around specific areas like Internet shopping, restaurants and travel.
Google declined to comment “beyond what we’ve said in our blogs already.”
As part of the antitrust case that was outlined in April, Margrethe Vestager, Europe’s top competition chief, had focused specifically on Google’s comparison shopping site, saying the company diverted traffic unfairly from competitors to its own services.
Analysts, however, say the initial focus on Google’s comparison shopping service may lead to a broader stance toward the company’s other search products like travel and online mapping.
“If the investigation confirmed our concerns, Google would have to face the legal consequences and change the way it does business in Europe,” Ms. Vestager said in April, referring to Google’s search practices.
The move against Google is the first time that European antitrust officials have brought charges against the tech giant. The company, which vigorously denies the accusations, may still settle the case and has until the end of the month to respond to the European charges.
If Google fails to rebut the formal charges, Ms. Vestager could issue a fine that could exceed $6.5 billion — about 10 percent of Google’s most recent annual revenue. The largest single fine yet issued in such a case, however, fell significantly short of that. It was $1.2 billion in 2009 against Intel for abusing its dominance of the computer chip market.