New government guidelines for targeted web advertising based on users' activities do not go far enough to protect privacy, US privacy groups say.
The World Privacy Forum has accused the Federal Trade Commission (FTC) of ignoring requests to keep genetic and other highly sensitive information private, according to US media reports.
The Center for Digital Democracy said the FTC had failed to recognise that a vast commercial surveillance system is at the core of most search engines.
The new guidelines were drawn up to incorporate public comment on a set of principles published in 2007.
But the revised guidelines do not require Google or Yahoo to make any changes to their controversial behavioural targeting advertising systems.
The guidelines require websites to disclose the data they are collecting and allow users to opt out, provide reasonable security, keep promises on data handling, and obtain consent for sensitive data.
Privacy groups say that it is difficult for web users to keep track of the hundreds of sites collecting personal information so they can opt out of all these schemes.
Firms in the discussion include Google, Yahoo, BT's Revenue Science, Phorm, BBC and Reuters.
BT was accused of invading people's privacy when it conducted secret trials on an ad-serving technology from Phorm in 2006 and 2007.
Many privacy groups, including the UK's Information Commissioner's Office, want all behavioural advertising to be by choice and not automatic, but advertisers fear this could destroy their business model.