Charter Communications Inc. will hold off on plans to track customers' Internet use for a targeted-advertisement campaign after Connecticut's top legal officer said the service may be illegal.

Charter won't move forward with tests ``at this time'' after customers questioned the program, the company said today in a statement. Two members of Congress said last month that the plan raised privacy concerns because it would have shared consumers' Internet activities with third-party advertisers.

Connecticut Attorney General Richard Blumenthal echoed those comments today and called the cable-television company's plan ``potentially illegal'' in a statement. St. Louis-based Charter, the fourth-biggest U.S. cable company, and other providers have been looking to use their technology to sell ads based on customers' preferences.

``The arrangement raises strikingly significant questions, such as what other uses will be made of this highly sensitive information,'' Blumenthal said in a June 20 letter to Charter that was made public today. About 100,000 of Charter's 5.2 million customers are in Connecticut, company spokeswoman Anita Lamont said in an e-mail.

In May, U.S. Representatives Edward Markey, a Massachusetts Democrat, and Joe Barton, a Texas Republican, in a letter Charter Chief Executive Neil Smit asked Charter to delay the ad service, saying the plan ``raises substantial questions'' about compliance with privacy law.

Markey Pleased

Markey in an e-mail today said he was ``pleased'' by Charter's decision.

``I urge other broadband companies considering similar user profiling programs to similarly hold off on implementation while these important privacy concerns can be addressed,'' Markey said.

Charter's decision to hold off is ``good news,'' said Marvin Ammori, general counsel to Free Press, a Washington-based public interest group.

``We've been calling on Charter to press `pause' and wait for the law to catch up with the technology,'' Ammori said in an interview.

NebuAd Inc., Charter's proposed partner in the ad-targeting venture, welcomes discussions with lawmakers and others, the company said in an e-mailed statement.

The company works with Internet service providers ``to customize and improve services,'' according to the statement.

Charter fell 10 cents, or 8 percent, to $1.15 at 4 p.m. New York time in Nasdaq Stock Market trading.