Googlefiled with the European Union competition regulator on Friday for permission to buy rival DoubleClick for $3.1 billion, and the deal almost immediately became contentious.
The European Commission said it had set a review deadline of Oct. 26, when it could approve the deal, give a two-week extension or open an in-depth, four-month investigation.
"We are asking the European Commission to look at the proposed acquisition. We believe this deal is positive for both users and advertisers, and fosters competition," Julia Holtz, Google's competition counsel, told Reuters.
But rival Yahooimmediately issued its own statement over the deal, seeking an in-depth review.
"The deal raises important questions about the future of Internet advertising. These questions warrant an in-depth debate and review by a broad range of Internet publishers, advertisers, service providers and governments in Europe and elsewhere," said Toby Coppel, managing director of Yahoo Europe.
Others including Microsoftand AT&T have asked U.S. antitrust officials to look closely at the proposed takeover, saying Google could gain too much control over online advertising.
The Commission has already sent questionnaires asking competitors and customers what they think about the deal.
DoubleClick is in the business of online advertising, as is Web search provider Google. DoubleClick connects ad agencies, marketers and Web site publishers, and has more than 1,500 corporate clients.
Google has already filed with the U.S. Federal Trade Commission and with the Australian competition regulator.