The European Union threatened to levy fines on Google Inc. that would be large enough to act as a deterrent after accusing the U.S. search-engine giant of squeezing out rivals in the comparison-shopping market.

The EU’s competition watchdog told Google it could face a fine based on its Adwords revenue stemming from European users, according to a version of the statement of objections released to complainants and seen by Bloomberg.

The European Commission sent the full version of the document to Google in April, accusing the California-based company of abusing its dominance of the search-engine market by unfairly favoring its comparison shopping service above rivals since 2008.

"In the present case, the commission intends to set the fine at a level which will be sufficient to ensure deterrence," the EU said in the document. "The commission considers that, based on the facts described in this statement of objections, Google committed the infringement intentionally or, at the very least, negligently."

The EU’s patience with Google ran out after three settlement bids failed to satisfy critics, who said the owner of the world’s most-used search engine was wielding its power over search results to unfairly promote its own services and paid ads.

Sending antitrust objections, which lay out where the EU thinks Google is breaking the law, pushes the investigation into new territory.

Fines would be based on factors that revenue from Google’s AdWords services relating to clicks from European users; revenue from its price-comparison website; and revenue from product queries on its search engine, the commission said in the complaint.

The commission said it has reached the "preliminary conclusion that Google’s practice of positioning and displaying more favorably, in its general search result pages, its own comparison shopping service compared to competing comparison shipping services constitutes an abuse by Google in the relevant markets for general search services."

The commission declined to comment on the content of the statement of objections. Google representatives didn’t immediately respond to emails seeking comment.