Earlier this week Google began to warn surfers if a site they were about to visit was likely to contain malware downloads.

The search engine diverts users to a warning page prior to visiting the site. It's using data provided by StopBadware.org.

Shane Keats of rival service Siteadvisor is "delighted that Google's noticed it's a problem" but isn't concerned as Stopbadware.org's manual site review process has only catalogued 12 sites so far compared to the 6.4 million that Siteadvisor has.

Given that Siteadvisor has a large network of computers automatically crawling the web and installing/running whatever downloads it can find, we'll continue to trust it above the, so far, limited offering from Google.

Keats reckons that while "community has a really important part to play, automation is the only way for this to scale."

Google has highlighted the issue but it'll be interesting to see whether it follows through with so many other projects on its plate.

Keats, who helps maintain the Siteadvisor blog, questions Google's commitment: "We'll know how serious Google are if it flags websites in its sponsored listings as containing badware."