Google this week pledged to further crack down on access to child porn via its search engine.

“In the last three months [we] put more than 200 people to work developing new, state-of-the-art technology to tackle the problem,” Google executive chairman Eric Schmidt wrote in an op-ed(Opens in a new window) for The Daily Mail.

That includes fine tuning Google Search to prevent child porn-related imagery and links from appearing in results. “While no algorithm is perfect – and Google cannot prevent pedophiles adding new images to the Web – these changes have cleaned up the results for over 100,000 queries that might be related to the sexual abuse of kids,” Schmidt wrote. “As important, we will soon roll out these changes in more than 150 languages, so the impact will be truly global.”

Google has also added warnings atop search results for more than 13,000 phrases and terms, which “make clear that child sexual abuse is illegal and offer advice on where to get help,” he said.

One of the challenges of removing child porn from the Web is determining whether something is actually abusive. “Computers can’t reliably distinguish between innocent pictures of kids at bathtime and genuine abuse. So we always need to have a person review the images,” Schmidt said.

Once objectionable images are found, they are given a digital fingerprint that allows Google’s systems to identify them if they ever appear again. “Microsoft deserves a lot of credit for developing and sharing its picture detection technology,” Schmidt wrote.

Unfortunately, pedophiles are “increasingly filming their crimes,” Schmidt said. But engineers at YouTube have developed a technology to identify these videos, which is now in testing at Google and should be available to other Internet companies and organizations in the New Year.

Schmidt also pledged to send engineers to the U.K.’s Internet Watch Foundation and the U.S. National Center for Missing and Exploited Children (NCMEC), as well as fund internships for other engineers at these organizations.

“This will help the IWF and NCMEC stay one step ahead. The sexual abuse of children is a global challenge, and success depends on everyone working together – law enforcement, internet companies and charities,” Schmidt concluded. “We welcome the lead taken by the British Government, and hope that the technologies developed (and shared) by our industry will make a real difference in the fight against this terrible crime.”

Schmidt’s pledge comes several months after U.K. Prime Minister David Cameron announced plans to block Internet porn by default for all U.K. citizens. “By the end of this year, when someone sets up a new broadband account, the settings to install family friendly filters will be automatically selected,” Cameron said in July.

Tech firms like Google and Microsoft, meanwhile, have been going after child porn for years. Most recently, Google in June said it would spearhead a shareable database that should make it easier for organizations to report and remove images of child sexual abuse from larger portions of the Web.

Back in 2011, Facebook and Microsoft joined the National Center for Missing and Exploited Children’s (NCMEC) PhotoDNA program to combat child pornography.