Facebook, Google, Twitter and AOL have joined an alliance that has been set up to counter "bad ads", including those that deliver malware, direct users to scams, or try to sell counterfeit goods, said StopBadware, the promoters of the alliance.

The Ads Integrity Alliance was launched yesterday and has Interactive Advertising Bureau (IAB) in New York also as a charter member.

"No individual business or law enforcement agency can single-handedly eliminate these bad actors from the entire web," said Eric Davis, Google's global public policy manager.

Since 2006, StopBadware has enabled many websites, service providers and software providers to share real-time information in order to warn users and significantly eliminate malware on the web, Davis added.

StopBadware hosts the Badware Website Clearinghouse which lists websites identified and examined by partners such as Google as containing or linking to malware and related software, which the organisation calls "badware". The nonprofit organisation started as a project of the Berkman Center for Internet & Society at Harvard University.

The alliance has outlined general plans to develop and share definitions, industry policy recommendations, and best practices. It also plans to share information about "bad actors," and share relevant trends with policymakers and law enforcement agencies.

In 2011, Google said it disabled more than 130 million ads and 800,000 advertisers that violated its policies on its own and partners' sites, including ads that promote counterfeit goods and malware.

The problem is that when Google or another website shuts down a bad actor, that scammer often simply tries to advertise elsewhere, said Davis, while stressing the need for an industry-wide effort.