Google and Microsoft are cracking down on child pornography searches in Britain. Above, an employee types on a computer keyboard with both Latin and Cyrillic letters in Sofia in this June 23, 2008, file photo. (STOYAN NENOV/REUTERS)

Google and Microsoft have announced plans to censor search results that could direct users to child pornography, responding to pressure from British authorities.

Users using 100,000 search terms and phrases will no longer receive content related to the sexual abuse of kids on the companies’ English-language search engines, Google and Microsoft said.

Google and Microsoft will also give illegal pictures unique identifiers so that those images can be automatically deleted whenever they appear, the companies said. YouTube engineers are working on a similar identification process for videos, according to Google, which owns the video service.

In a column published in the Daily Mail newspaper Sunday, Google Executive Chairman Eric Schmidt said that some search terms related to child pornography will still return results, but British users will see a warning at the top of the search results page. The warning will note that the search returned potentially illegal results and direct the user to charities dedicated to fighting child pornography.

The efforts come after a major push from British politicians to impose stricter limits on Internet pornography. British Prime Minister David Cameron’s Conservative-led government pushed for a crackdown on Internet pornography after the rape and deaths of two young girls at the hands of men believed to be addicted to child pornography.

This fall, Cameron had called on search-engine operators such as Google and Microsoft to make it more difficult to find child pornography on the Internet.

Schmidt directly tied the new policies to Cameron’s remarks. “We've listened, and in the last three months put more than 200 people to work developing new, state-of-the-art technology to tackle the problem,” he said.

Schmidt said the changes will be implemented in more than 150 languages, although he did not say when that would happen.

Microsoft did not comment on whether it would expand its effort.

According to a report from the BBC, Cameron said that he welcomes the action by Google and Microsoft but that the companies must move quickly, or he will bring legislation on the matter.

There is some doubt that removing this content from broader search engines will get to the heart of the problem. According to the British Child Exploitation and Online Protection Center, searches through commercial search engines account for a “very small” percentage of porn transactions.

As part of the government’s push against Internet pornography of any form, British Internet service providers are compelled to install family-friendly filters automaically on Internet service, and British consumers must also tell their providers whether or not they want access to any online pornography. The push has led to some debate over whether the measures are leading the country into a gray area on the proper balance between online censorship and free speech. There is little argument that illegal content, particularly child pornography, should be blocked from the Web. The question is how narrowly companies are able to focus their efforts.

Jillian York, director for International Freedom of Expression at the Electronic Frontier Foundation, said that Microsoft has a good record for removing illegal content from its search engine. But when those efforts are extended to other languages, she said, the firm has ended up blocking more than it intended. A censorship block on the word “breast” in its Arabic search, for example, prevented anyone from getting information on breast cancer.

“It’s a matter of getting the implementation right so that there’s no collateral damage,” she said.