Websites are under pressure to allow consumers much greater control over how they are tracked online. But work undertaken by the World Wide Web Consortium (W3C) to create a Do Not Track (DNT) standard was "not going to plan", said Ms Kroes.
She praised browser manufacturers who had incorporated DNT technology but said that it was not enough.
It should be built on the principle of informed consent, giving people control over their information. And, indeed, it must be designed to let people choose not to be tracked. The clue is in the name — do not track
She is angry about delays and a proposal to exempt marketing. She is concerned by suggestions that DNT might not be set as a default.
Much of the anger is reserved for the Direct Marketing Association (DMA), which has asked the W3C that marketing be added to the list of those activities exempt from the standard.