Google is winning the war on fraudulent and dangerous advertisements, the company claimed on Wednesday.
According to a blog post by engineering chief Sridhar Ramaswamy, in 2011 Google disabled more than 130 million "bad ads". He said this meant Google had "reduced the percentage of bad ads by more than 50 percent compared with 2010".
"Online advertising is the commercial lifeblood of the web, so it’s vital that people can trust the ads on Google and the Internet overall," Ramaswamy wrote.
"Like all other internet companies, we're fighting a war against a huge number of bad actors — from websites selling counterfeit goods and fraudulent tickets to underground international operations trying to spread malware and spyware," he added. "We must remain vigilant because scammers will always try to find new ways to abuse our systems."
Ramaswamy said Google was catching most scam ads before they go up. He pointed out that, during 2011, 150,000 accounts had been shut down for "attempting to advertise counterfeit goods", with more than 95 percent of those accounts being "discovered through [Google's] own detection efforts and risk models".
Bad ads have sometimes landed Google in very hot water. It had to pay a $500m (£306m) fine to US authorities last August to settle a row over illegal drug ads. As part of the settlement, Google also agreed to beef up its processes for taking down fraudulent advertising from its search and other products.
According to Ramaswamy, Google's systems automatically scan the landing pages being linked to in ads to check their content, and the company has "widened [its] proactive monitoring of sensitive keywords and queries related to counterfeit goods".
"Our computer scanning depends on detailed risk models to determine whether a particular ad may violate our policies, and we recently upgraded our engineering system with a new 'risk model' that is even more precise in detecting advertisers who violate our policies," Ramaswamy wrote.
The company has also recently updated its policies to crack down on short-term loan advertisers, to ensure that they disclose "fine-print details" up-front, he noted.
Google said last June that complaints from UK consumer protection authorities alone had led it to take down 93,000 scam ads over a six-month period.