WASHINGTON DC: US lawmakers have expressed grave concens over Google's proposed $3.1 billion (€2.09bn; £1.5bn) acquisition of online advertising brokerage DoubleClick.

Senators Herb Kohl and Orrin Hatch, who head the Senate's antitrust panel, issued a stern warning to Federal Trade Commission chairman Deborah Platt Majoras.

"Antitrust regulators need to be wary to guard against the creation of a powerful internet conglomerate able to extend its market power in one market into adjacent markets to the detriment of competition and consumers.

"We therefore urge that the FTC only approve this merger if it concludes after completing a comprehensive investigation that this merger will not cause substantial injury to competition."

The controversial deal is also under intense scrutiny by European Commission competition regulators.

Data sourced from Adweek (USA); additional content by WARC staff