WASHINGTON (Reuters) - The Federal Trade Commission is conducting an informal probe into whether DoubleClick Inc. (NasdaqNM:DCLK - news) engaged in unfair or deceptive practices in collecting and maintaining data concerning Internet users.

DoubleClick, the leading company placing banner ads on Web sites, said it received a letter from the federal consumer watchdog agency on Feb. 8 and is cooperating with the inquiry, according to a filing with the Securities and Exchange Commission.

A spokesman for the FTC declined to comment.

The company could not be reached immediately for comment.

DoubleClick's disclosure was found amid the details of a lengthy amended registration statement to sell 7.5 million shares of stock that was filed with the SEC on Feb 14.

Controversy about the company erupted last month when DoubleClick revealed a new plan to track Internet user's movements on the Web and combine that data with people's real names and addresses.

The plan is not yet in effect, the company has said.

Currently, DoubleClick assigns a unique tracking number to each Web surfer that visit one of about 1,500 sites where the company places ads but without linking the information to real names and addresses.

The new plan drew complaints from privacy groups, leading to a consumer boycott and a complaint filed with the FTC on Feb. 10. A handful of consumers have also filed civil lawsuits against the company.

In an attempt to address the complaints, DoubleClick on Monday unveiled five new privacy initiatives, including a media campaign to educate consumers through ads and a Web site called http://www.privacychoices.org.