IDG News Service — The European Commission is investigating allegations that Google (GOOG) has abused its dominant position in online search to promote its other services, such as price comparators, the Commission announced Tuesday.

The investigation will also look into suspected restrictions on the portability of online advertising campaign data to competing online advertising platforms.

A Google spokesman responded to this allegation saying that the Internet giant does provide advertisers with the ability to export their ad campaigns to other platforms. However, he added that Google does limit the ability of ad agencies to use AdWords API to copy campaign data automatically from one screen to another. "This restriction is designed to ensure that if an agency is placing ads across several search engines, it doesn't play to the lowest common denominator -- which would hamper any new innovations in AdWords that our competitors didn't adopt, too," he said.

The investigation will also examine alleged abuse of exclusivity clauses that discourage sites carrying advertisements served by Google from also carrying advertisements served by its rivals.

PC manufacturers and software developers will be questioned to see whether they were pressured by Google to make its search service the default in their products, the Commission said.

The investigation was launched following a preliminary examination of complaints received by the Commission in February from by French legal search engine ejustice.fr and by two price comparators, Foundem of the U.K. and Ciao of Germany.

The companies claim that Google has treated their services unfavorably. They also alleged that Google gave its own services preferential placement. The Commission is particularly concerned that Google may have lowered the ranking in its search results of rival providers of services such as price comparators, in order to promote similar services of its own.

However Google sources have hit back at the complainants saying that international rival Microsoft (MSFT) has a hand in two of the complaints. Microsoft owns Ciao and has assisted Foundem to lobby in multiple cities around the world through an organization called ICOMP. Foundem has alleged that Google's algorithm pushes the shopping site down in its rankings because it considers it a competitor. Ejustice.fr's complaint is based on similar grounds.

Last week, a U.S. researcher published details of his investigation into Google's treatment of its own supplementary search services compared to those of its rivals.

Authorities in the U.S. have also been examining Google's dominant market position, but have not brought any formal proceedings. However in the E.U. Google controls more than 80 percent of the online search market. The company already faces separate antitrust inquiries in Italy, Germany and France.

The Commission said that opening the investigation does not imply that it already has proof of any infringements: merely that it is looking for it. It added that the length of the investigation will depend to some extent on the company's cooperation. There is no legal deadline to complete inquiries -- the regulators' investigation into Microsoft over competition issues related to its Windows operating system took more than 10 years to resolve.

The Commission can fine companies up to 10 percent of global turnover for breaching E.U. competition rules.