WASHINGTON (Reuters) - A prominent privacy group on Thursday filed a complaint with the Federal Trade Commission accusing Internet advertising firm DoubleClick Inc. (NasdaqNM:DCLK - news) of misleading millions of consumers.

The non-profit Electronic Privacy Information Center said DoubleClick's plan to track Internet users as they moved through the World Wide Web and link the data with people's actual names and addresses was deceptive and unfair.

The group asked the FTC to stop DoubleClick's data collection program until it obtained explicit permission from all involved consumers. DoubleClick should destroy all previously collected data and pay a fine equal to 50 percent of revenue from the practice, the group said.

DoubleClick denied violating laws against deceptive and unfair trade, noting that consumers would have the opportunity to opt out of its new tracking scheme.

``DoubleClick will only combine offline and online information when the user has been given prior notice and choice, and therefore this complaint is without merit,'' the company said in a statement.

Separately, a U.S. senator introduced legislation to require that all Internet companies get explicit approval before collecting data or tracking Web surfers. ``The fundamental right to privacy should not be sacrificed to the information age,'' Sen. Robert Torricelli, Democrat of New Jersey, said.

Officials at the privacy center said DoubleClick's notices and policies contradicted assurances it had made in previous years and were unlikely to catch the attention of many consumers.

``This complaint against DoubleClick is a critical test of the current state of privacy protection in the United States,'' said Marc Rotenberg, executive director of the center.

``We are looking to the Federal Trade Commission to see whether companies that break their promises and collect personal information in an unfair and deceptive manner will be held accountable.''

DoubleClick places ads on thousands of Web sites, including those of AltaVista, Major League Baseball and PBS Online. On about 1,500 sites, the company also places a unique identification code on the computers of Web visitors and then tracks the activities of those surfers. But the profiles are not linked to people's actual names and addresses.

In January, the company disclosed plans to create a program that would match people's names with their Web surfing activity. The program has not started yet and would only involve Web sites that notified consumers and offered a chance to opt out, the company said.