The Americans always consider the privacy of the individual to be of paramount importance. In such a scenario, the targeted delivery of online advertising based on consumers' surfing habits has given cause for concern and invited a US Congressional inquiry into the antecedents of such companies.

In regard with this investigation, the House Energy and Commerce Committee has asked 33 top cable, phone and Internet companies to provide information on their data collection practices.

Besides the usual suspects Google, Microsoft and Yahoo, other notable names in the list include AOL, AT&T, Comcast, Cox, Time Warner Cable and Verizon.

Notices have also been sent to Bresnan Communications, Bright House Networks, Cable One, Cablevision, Cbeyond, CenturyTel, Charter Communications, Citizen Communications, Covad Communications, EarthLink, Insight, Knology, Level 3 Communications, Mediacom, Paetec, Qwest, RCN, Suddenlink, TW Telecom, WideOpenWest, TDS Telecom, United Online, Windstream Communications and XO Communications.

The Committee asked a total of 11 questions that the companies are required to answer by Friday, 8 August. Among them, the companies are asked to describe the nature and extent of any of their targeted Internet practice, if they engaged in such activities, to explain if such practices have had any limitations regarding health, financial and other sensitive personal data, as well as the nature of those limitations.

Furthermore, the companies were asked to provide the criteria for choosing the communities to be targeted, the number of consumers subjected to such practices, whether the consumers have been notified, including a copy of the notification, the status of the consumer data collected and whether the data had been destroyed or is routinely destroyed, and more

"The Committee is interested in learning how pervasive this practice is among cable, phone, and Internet companies, what safeguards are in place to ensure that consumers are aware of the practice, and how best to preserve their privacy," committee Chairman John D Dingell, the Democrat congressman from Michigan, said in the letter.

Chairman Edward J Markey of the Telecommunications and the Internet Subcommittee, also a signatory to the letter, said, ''Privacy is a cornerstone of freedom. Online users have the right to explicitly know when their broadband provider is tracking their activity and collecting potential sensitive and personal information.''

Internet companies and ISPs routinely track users' activity online in order to serve up more targeted advertisements. Whether or not the data that is collected contains personally identifiable information has been a point of contention.

Internet companies insist that the compiled information – which can include IP addresses, Internet provider, or Web sites visited – is completely anonymous, but detractors point to incidents like a 2006 AOL data leak, which mistakenly released 20 million search queries that included identifiable data.

Microsoft told the Senate Commerce Committee last month that it keeps its Live Search data separate from account information, serves up targeted ads based on unidentifiable data, and anonymizes all of its query data after 18 months.

Google said at the same hearing that it has a similar policy.