ALBANY - By the end of the month, newsgroups featuring thousands of images depicting child pornography will be stricken from three of the top five Internet providers in the nation.

Verizon, Sprint and Time Warner Cable agreed with New York Attorney General Andrew Cuomo to block access to child pornography disseminated through newsgroups and user groups, a hard-to-regulate sector of the Internet designed to bring together users with like interests and cloaked in privacy.

With the agreement announced Tuesday, Cuomo skipped over the untold number of individual users accessing child porn and went to the portals that, unwittingly they all say, provided the route to sharing the illegal obsession.

Cuomo said the service providers will block child pornography on the sites, which are designed for private communications and are difficult to police because of their numbers and privacy concerns.

The companies also agreed to eliminate the material from their servers and will pay $1.125 million to help fund efforts to remove child porn from the Internet.

The agreements follow an undercover investigation of child porn newsgroups and will affect customers nationwide.

But, as Cuomo said, such online pornography is a difficult syndrome to stop. When one point of Web access is closed, the same perpetrators are likely to open another. And his agreements with the online services end at the nation's borders.

“They are very inventive and obviously a lot of this industry moves offshore very quickly,” said Professor Christine Corcos of the Louisiana State University Law Center. “As long as the people who produce this material think they have markets, and they think they can reach that market, they are going to continue and the thing is they can just move to other countries.”

She also notes the concerns of advocates of greater freedom on the Internet who believe a crackdown like Cuomo's could squelch freedom of speech among legitimate Internet groups.

Cuomo's investigators found 88 newsgroups devoted to child pornography in an investigation they said took six to eight months. More than 11,000 images were collected using software that identifies child pornography by tracking patterns in the pixels of the images.

Cuomo said the companies acted immediately when told of the concern.

He said the key is going after the Internet providers rather than trying to prosecute thousands of users posting the pornography.

“There's no doubt this is a tough issue,” Cuomo said at a news conference.

“People are very creative and there is a market for this filth,” he said. “We have to work together.”

Time Warner Cable acted when it learned users were posting objectionable material and eliminated the newsgroups, a mainstay of the Internet from its early days, said corporate spokesman Alex Dudley.

“We are not admitting to any guilt,” he said of the agreement with Cuomo.

He emphasized that Time Warner didn't host or provide any of the content and was simply a portal, allowing groups to be created with content provided by the users.

“As soon as we were made aware of the issue ... we took steps to correct,” Dudley said Tuesday.

Verizon admits no guilt and was never accused of wrongdoing, said Eric Rabe, vice president for communications at Verizon.

He said when concerns were raised about some of the tens of thousands of newsgroups, Verizon acted immediately to shut down the sites.

“There are people doing whatever they do on the Internet all the time and we can't possibly scan every use group,” he said. “But there are some things we can do and as soon as it's brought to our attention, we work very quickly.”

“The tension there is between allowing customers the ability to communicate with their privacy rights protected and preventing people from doing things that are illegal,” Rabe said.

“We are doing our part to deter the accessibility of such harmful content through the internet and we are providing monetary resources that will go toward the identification and removal of online child pornography,” said Sprint Senior Public Affairs Manager Matthew Sullivan. “We embrace this opportunity to build upon our own long-standing commitment to online child safety.”

Verizon and Time Warner Cable are two of the five largest Internet service providers in the world. Verizon has 8.2 million subscribers and Time Warner Cable's Road Runner has 7.9 million. Sprint is one of the three largest wireless companies in the United States.

Cuomo said his investigation of two other large national service providers is continuing, but he wouldn't name them.

He has used similar probes and the possibility of civil or criminal charges to extract concessions on Internet safety in the past.

Last year, Cuomo reached agreement with the social networking sites MySpace and Facebook to toughen protections against online sexual predators.