The announcement follows on from a routine privacy enquiry from the European Union's data privacy panel, which is looking at all aspects of internet privacy issues.

The move will, the company says, make Bing – a rival to the popular Google and Yahoo web search engines – a "better choice" for privacy-conscious internet users.

Google is reported to keep its users search engine data for around two years, although anecdotal evidence suggests that registered users of the Google portal – including Gmail users – can access their search data for much longer periods.

Yahoo, meanwhile, whilst not stating how long its IP-based search records are stored, claims that its data is "anonymised" after six months, suggesting that a net trace on a given search would be technically difficult.

"We believe that the balance between privacy and efficiency is very much in the mind of consumers", Microsoft's associate general counsel John Vassallo told reporters yesterday.

"Getting the balance right does make the search engine more attractive", Microsoft's Vassallo added.

EU data protection officials, meanwhile, have publicly questioned the need for search engines to keep data on searches and had asked for a voluntary six month limit, although there are no reports that the EU will change the law to accommodate this recommendation.