BRUSSELS: Google's proposed $3.1 billion (€2.1bn; £1.49bn) acquisition of online advertising services firm DoubleClick has now come under the heavyweight scrutiny of the European Commission's antitrust regulator.

The deal has caused much denture-gnashing among Google's rivals, advertising bodies and privacy advocates in the US and in Europe, all of whom claim it allows the search giant undue control of ad sales and too much information about web users.

The EC's probe into whether the union of Google's ad-selling network and DoubleClick's ad-serving platform will shut out competitors will run until April 2. However, privacy issues are not within its remit.

Google ceo Eric Schmidt says the company is disappointed by the watchdog's decision and claims the time frame will allow competitors, such as Microsoft and Yahoo, to consolidate their own recent acquisitions.

Across the pond, the deal is also being examined by the Federal Trade Commission. Its opponents are hoping the EC review will persuade the US regulator to impose restrictions if the green light is given.

Data sourced from Wall Street Journal Online; additional content by WARC staff