SAN FRANCISCO -- Google on Monday launched a long-anticipated medical records service letting US users store and manage their health care information online.

Amid concerns over privacy, Google said it has built a secure computer platform separate from its search system to host medical records as part of an emphasis on keeping the health information protected.

"We have put in place the firmest privacy policy we can construct," Google vice president of search product and user experience Marissa Mayer said during a press event at the Internet giant's headquarters in Mountain View, California.

"It is our highest level of security."

Google Health has links to pharmacies, clinics and diagnostic labs. The service is free and enables people to have electronic copies of information such as prescriptions, lab test results, hospital stays, and medical conditions stored on Google computers.

Users of the service dictate how the information is shared.

For example, a user could set up a pre-existing relationship with hospital so that in case of emergency, his or her personal medical history could be instantly available to emergency room doctors.

Or, someone planning an exotic vacation could check the vaccinations they have or might need.

"Google, on your behalf, is storing a copy of your records," Google Health product manager Roni Zeiger said after demonstrating the service.

"This is a user controlled database that Google is hosting."

Google said it has crafted protected online connections with a host of major US medical service providers and is open to working with other health care outlets interested in crafting software to join the network.