Google has begun issuing warnings to users if they are about to access a site containing harmful code.
Forming part of the 'Stop Badware' initiative, the alerts appear if users click on a link to a page known to host spyware or other malicious programmes.
The alerts suggest that users might want to visit a different site, but doesn't prevent them from continuing to the site they have chosen.
Google, Lenovo and Sun set up the Stop Badware coalition in January to catalogue sites that contain dangerous code. The group is also backed by Harvard and Oxford Universities.
The warnings currently link users to a generic page on the organisation's website, but the organisation said it would eventually provide detailed reports on individual sites.
"Hopefully this next step will bring us that much closer to fulfilling our mission of providing people with reliable, objective information about downloadable applications in order to help them make better choices," said a statement on the group's site.