Online travel agency Expedia on Friday accused Google of breaching EU rules with a formal complaint to EU antitrust regulators as it joined a dozen other firms that have taken their case to the European Commission in the last two years.

The EU watchdog is now investigating the world's most popular search engine after rivals, including Microsoft, accused Google of abusing its dominant position in the market for Web search engines.

EU Competition Commissioner Joaquin Almunia said earlier this week that he would decide after Easter whether to formally charge Google or drop the investigation.

Expedia said it had details of specific business and search practices by Google that violated EU competition and consumer protection laws.

The complaint offers evidence of how Google's conduct harms not only competition, but consumers, Brent Thompson, senior vice president of government affairs, said in a statement.

Expedia believes that strong action is needed by the European Commission to restore a fair and competitive marketplace in online search that respects consumers' rights, he said.

Google said it has not been informed of the complaint yet.

We haven't seen the complaint yet, but we've been working to explain how our business works, cooperating with the European Commission since this investigation began, Google spokesman Al Verney said in a statement.

Because there's always room for improvement, we're happy to discuss any concerns the Commission might have, he said.

There are now 12 complaints with the EU watchdog, the majority of them small competitors across Europe, which claimed that Google demoted their sites and promoted its own services. Google has denied that it stifles competition.

U.S. enforcers are also investigating Google which controls more than two-thirds of the global search market.

EU privacy regulators are also scrutinizing Google's new privacy policy which came into effect on March 1.

(Reporting by Foo Yun Chee; Editing by Gary Hill)