European Union regulators have launched an in-depth investigation into Google's $3.1bn (£1.5bn) takeover of online advertising firm DoubleClick.
The EU Commission said its initial probe had shown the deal would raise competition concerns.
It has set itself a deadline of 2 April 2008 to reach a decision.
Google said it would work with the Commission to show how the acquisition would benefit publishers, advertisers and consumers.
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