The large size of Silicon Valley-based Google matters to European Union which announced an antitrust investigation into accusations that the internet search giant was rigging the online search market.

Google has been accused of giving "unfavorable treatment" to small companies’ services in both unpaid as well as sponsored search results.

Up until now, the Silicon Valley giant has faced probes focused on particular acquisitions or narrow complaints. Rumoured deal that the company would acquire online discount coupon firm Groupon Inc. will also trigger an antitrust probe.

The new investigation announced by European Union will try to determine if Google has misused its search-engine dominance to hush up online rivals.

European regulators will probe if Google lowered the ranking of rivals in the unpaid search results displayed under the self-styled sponsored links, for which Google received payments.

However, Google defended itself, claiming its search services were fair and transparent.

Commenting on the topic of probe by European regulators, the company said, "We've always focused on putting the user first by providing the best possible answers as quickly as possible.”

Analysts are of the view that Google is paying a price for behaving as if it can do whatever it wants and get away with it.