Do you continue to search and surf unconcerned about the tracks you’re leaving on the Web? Perhaps you should be concerned; it’s certainly concerning politicians and bureaucrats in Europe.

A European Commission advisory body on data protection is recommending that search engines should delete personal data held about their users within six months – a recommendation that the Commission is likely to accept.

Such a move has already drawn an irritable response from Google, which says its privacy policy "strikes the right balance" between privacy, security and innovation. Google, which has previously tried to address privacy concerns expressed by users, anonymises its search data after 18 months, as does Yahoo. MSN does this after 13 months.

Peter Fleischer, Google's global privacy counsel, said in a statement: "Google takes privacy incredibly seriously; protecting our users' privacy is at the heart of all our products. It is the reason we were the first company to commit to anonymising our search logs, and also why we dramatically shortened our preference cookie lifetime."

Every search you make of the Web is stored somewhere by the search engine you use. It also stores your computer’s IP address, information about how you made your search, and your search history.

The European Commission’s working party says the reasons why this data is kept have been “insufficiently explained”.

This data is bread and butter for the search engines. Statistics gleaned from it enable them to determine the most popular search topics at any given time. Advertisers pay handsomely for this information, buying space on the search engine’s pages, inviting users to click on paid links.

The working party says the personal data of users should not be stored or processed "beyond providing search results" if the user had not created an account or registered with the search engine, and that data should not be collected to serve personalised adverts without consent. It should also not be stored for accountancy purposes, or to improve services.

The working party’s report says search engine users should have the right to inspect and correct stored personal data, and that search engines should be forbidden from enriching stored data with third-party information except by explicit consent.

While the big search engines, like Google, are based outside the European Union’s jurisdiction, any legal restraints on storing data from European-based users could restrict the search engine’s ability to customise searches for people based in particular countries. This might encourage the establishment of locally-based search engines, giving the global giants unwanted competition in the vast European market.

If European politicians act on these recommendations, the big search engines could face lengthy, expensive court action to defend their interests. The media will perceive it as a Europe vs America tussle, with all the associated nationalistic baggage.

Meanwhile, a computer security researcher at Cambridge University says the online advertising system known as Phorm is illegal.

Phorm works by taking a copy of the traffic generated when a user visits a Web site, analyses the text in this traffic and then uses the resulting information to insert targeted adverts on sites that have signed up.

Dr Richard Clayton says his research supports assertions that this is a breach of privacy, as the users concerned don’t know their data is being examined.

Phorm is due to undergo large-scale testing by British Telecom, and Britain’s Information Commissioner’s Office says it will be monitoring Phorm as it nears deployment.

The company behind Phorm says it is confident it complies with UK laws.