(Patrick T. Fallon/Bloomberg News)

AT&T and Verizon are withdrawing much of their advertising from Google amid a widening backlash against the Internet giant's algorithmic ad-placement software.

Wednesday's decision reflects concern by the country's biggest telecom companies that Google's automated systems could be placing their ads beside extremist content and on websites that promote hate speech.

“We are deeply concerned that our ads may have appeared alongside YouTube content promoting terrorism and hate,” AT&T said in a statement. “Until Google can ensure this won’t happen again, we are removing our ads from Google’s non-search platforms.”

In a statement, Verizon said it took “immediate action to suspend this type of ad placement” after it learned that its ads were appearing on “non-sanctioned websites.”

Although the decisions do not appear to affect ads that the companies place next to Google search results, they nevertheless cover a wide swath of the Internet that is connected to Google's vast ad network. AT&T and Verizon are among the world's largest advertisers, and their move makes them among the first U.S. businesses to withdraw their marketing after a similar outcry in Europe prompted Google to adjust its advertising policies this week. The Guardian, a British newspaper, pulled its advertising from Google and YouTube this month amid complaints that its ads were appearing next to videos of white nationalists and Islamist extremists.

“We’ve begun an extensive review of our advertising policies and have made a public commitment to put in place changes that give brands more control over where their ads appear,” Google said Wednesday in a statement. “We're also raising the bar for our ads’ policies to further safeguard our advertisers’ brands.”

Although tech companies such as Google have sought to position themselves as neutral platforms for technology, their growing role in consumers' everyday lives has forced them to make tough decisions about when and how to manage content appearing on their services. Selling ad space against offensive speech that targets racial minorities, women or other groups, critics argue, also poses an ethical quandary for Google, a company that portrays itself as inclusive and open.

Google's advertising operations are highly automated and deal with countless websites around the world. Grappling with hate speech at that scale poses a challenge, company officials conceded in a blog post Monday. But, they vowed, Google will work harder to take down ads when they appear next to content that is deemed hateful. The company also promised to give advertisers better control over where their ads appear — such as making it easier to blacklist certain types of content or sites where an advertiser does not want an ad to show up.