Google's proposed acquisition of DoubleClick does not pose a significant threat to competition in the European online advertising market, the European Commission said Tuesday. However, it reminded the companies that they also have an obligation to respect European Union legislation on the privacy of personal data, one of the grounds on which opponents lobbied to block the merger.

The E.U.'s competition regulator reached its decision after a four-month in-depth investigation of the US$3.1 billion merger, which received the approval of the U.S. Federal Trade Commission in December.

The deal is unlikely to harm consumers in ad serving or online advertising intermediation markets, the Commission said.

A merger of Google and DoubleClick will not hurt competition because the companies are not competitors, the Commission said: Google provides online advertising space on its own sites and, as operator of the AdSense service, an intermediary between publishers and advertisers, while DoubleClick offers ad serving, management and reporting services to publishers, advertisers and agencies.

The Commission also examined the risk of Google tying sales of its services to use of those of DoubleClick, or vice versa, to boost revenue. However, it concluded that Microsoft, Yahoo and AOL present sufficiently strong market alternatives that a merged Google-DoubleClick would be unable to exploit the link in that way.

Tuesday's decision only relates to E.U. merger regulations, the Commission said, and does not alter the merged entity's obligations under E.U. law on the protection of individuals and the protection of privacy related to the processing of personal data.