BRUSSELS — European Union regulators will investigate whether Google has abused its dominant position in the online search market — the first major probe into the online giant’s business practices.

The move announced today follows complaints from rival search engines that Google put them at a disadvantage in both its regular and sponsored search results, by listing links to their sites below references to its own services in an attempt to shut them out of the market.

The EU Commission will also see whether Google prevented advertising partners from placing ads from competitors on their sites. Competitors allegedly shut out include computer and software vendors, the commission said.

If the Commission finds that Google has abused its market position, the company could be fined up to 10 percent of its revenue — that would put it on the line for a $2.4 billion fine based on 2009 earnings figures.

The Commission has shown resolve in confronting U.S. corporations and only last year concluded a long-running antitrust case involving Microsoft that resulted in more than $1 billion of fines.

Three companies — U.K.-based price-comparison site Foundem, French legal search engine ejustice.fr and Microsoft-owned shopping site Ciao — lodged complaints against Google with the commission in February.

Google has maintained it is confident that it hasn’t done anything wrong.

“Since we started Google we have worked hard to do the right thing by our users and our industry — ensuring that ads are always clearly marked, making it easy for users and advertisers to take their data with them when they switch services, and investing heavily in open source projects,” Google said in an emailed statement.