The U.S. Department of Justice signed off on the deal in December, meaning Google has cleared its last major hurdle before acquiring DoubleClick.

Rivals Yahoo Inc. and Microsoft Corp., as well as advertisers and privacy advocates, have sought to block the takeover, claiming Google Inc. would have too much control over the online ad market.

The European Commission dismissed those objections, saying it found no proof that Google and DoubleClick would be able to marginalize competitors because Microsoft, Yahoo and AOL provided "credible" alternatives for placing ads on Web sites.

Google and DoubleClick are not rivals and even if they were, Google's acquisition would not have an adverse impact on competition, regulators found.

Regulators said their decision was based exclusively on the economic aspects of the deal and it had no bearing on the companies' obligations under EU personal privacy protection rules or how personal data is processed.

European privacy regulators are now examining if the data protection policies of search engines comply with existing EU law. A report is due in April. Regulators said last month that rules would also apply to search engines headquartered outside Europe.

New York-based DoubleClick helps its customers place and track online advertising, including search ads, which Google -- more than its nearest search competitors Yahoo and Microsoft -- has turned into a lucrative business. It places ads on Web pages that targeted consumers are likely to use, generating money for smaller publishers and lesser-visited pages.