Three public-interest groups are expected to file a joint complaint on Friday with the Federal Trade Commission calling for an investigation into the potential threat to consumer privacy posed by Google's planned acquisition of DoubleClick.

The Washington-based Electronic Privacy Information Center (EPIC), along with the Center for Digital Democracy (CDD) and the U.S. Public Interest Research Groups (U.S. PIRG), are asking the FTC to stop the $3.1 billion merger until the trade commission investigates Google's data collection and storage practices, orders DoubleClick to sweep out its data storehouse and requires the search giant to offer a public plan for safeguarding consumer privacy.