The pilot project announced yesterday will involve 1,500 to 10,000 patients at the Cleveland Clinic who volunteered to an electronic transfer of their personal health records so that they can be retrieved through Google's new service, which will not be open to the general public.

Each health profile, including information about prescriptions, allergies and medical histories, will be protected by a password that would also be required to use other Google services such as e-mail and personalised search tools.

Google views its expansion into health records management as a logical extension because its search engine already processes millions of requests from people trying to find more information about an injury, illness or recommended treatment.

But the health venture will also provide more fodder for privacy watchdogs who believe that Google already knows too much about the interests and habits of its users, as its computers log their search requests and store their e-mail discussions.

Prodded by the criticism, Google last year introduced a new system that purges people's search records after 18 months. In a show of its commitment to privacy , Google also successfully rebuffed the United States Justice Department's demand to examine millions of its users' search requests in a court battle two years ago.

The California-based company has not specified a timetable for unveiling the health service, which has been the source of much speculation for the past two years. Ms Marissa Mayer, the Google executive overseeing the project, had previously said the service would debut this year.

A Google spokesman contacted on Wednesday declined to elaborate on the company's plans. The Associated Press learned about the pilot project from the Cleveland Clinic, a not-for-profit medical centre founded 87 years ago.

The clinic already keeps the personal health records of more than 120,000 patients on its own online service called MyChart. Patients who transfer the information to Google would still be able to get the data quickly, even if they were no longer being treated by the Cleveland Clinic.

'We believe patients should be able to easily access and manage their own health information,' Ms Mayer said in a statement supplied by the Cleveland Clinic.

The Cleveland Clinic decided to work with Google 'to create a more efficient and effective national health-care system', said the medical centre's chief information officer C. Martin Harris.

Google is not the first high-tech heavyweight to set up an online filing cabinet in an effort to make it easier for people to get their medical records after they change doctors or health insurance plans.

Rival Microsoft Corp last year introduced a similar service called HealthVault, and America Online co-founder Steve Case is backing Revolution Health, which also offers online tools for managing personal health histories.

The third-party services are troublesome because they are not covered by the Health Insurance Portability and Accountability Act, or Hippa, said Ms Pam Dixon, executive director of the World Privacy Forum, which just issued a cautionary report on the topic.

If medical records are not protected by Hippa, the information could conceivably also be used for marketing purposes.

ASSOCIATED PRESS