A handful of top Internet companies announced a joint effort on Thursday to crack down on ads that promote counterfeit goods or include malware.
Google, Twitter, Facebook, and AOL joined the Interactive Advertizing Bureau to create the Ads Integrity Alliance to coordinate efforts and share information to prevent bad ads from popping up on their websites.
"No individual business or law enforcement agency can single-handedly eliminate these bad actors from the entire web," Google's Eric Davis wrote in a blog post.
In 2011 Google removed 130 million ads and blocked 800,000 advertisers that violated its policies, Davis said.
Last year, Google also agreed to pay $500 million to settle government charges that it had knowingly allowed ads for fraudulent Canadian pharmacies.