Last week, Charter Communications and NebuAd announced a plan to deliver better targeted ads to Charter's high-speed internet customers. Lawmakers are already calling foul.

The cable company sent letters to customers in four markets informing them of the company plans to start tracking every site they visit on the web. Charter plans to sell that data to behavioral targeting firm NebuAd, which would in turn use it to show relevant ads to Charter customers.

Two lawmakers, Reps. Edward Markey (D-MA) and Joe Barton (R-TX), have sent a letter to Charter asking it to put the brakes on the advertising plan until they "have an opportunity to discuss with you the issues raised by this proposed venture."

The issues they refer to deal with privacy.

"Any service to which a subscriber does not affirmatively subscribe and that can result in the collection of information about the web-related habits and interests of a subscriber ... raises substantial questions," the legislators wrote.

Charter claims the data collected from customers is not associated with user names, and that subscribers will have an opportunity to opt-out of the program. The company says it will also not track or provide targeted advertising based on confidential medical information, racial or ethnic origin, religious beliefs or sexual content, and will not target ads to children under the age of 13.

NebuAd adds: "The NebuAd system is built from the ground up to protect the privacy of users accessing the internet."

Charter stated on Friday that the company's "goal is to bring an enhanced internet experience to our customer while meeting all privacy protection requirements. We believe we have done that but are pleased to discuss this matter with the Chairman and the Congressman."

Stay tuned.