Two of the largest Internet service providers, AT&T and America Online, have reached agreements with the state attorney general, Andrew M. Cuomo, to eliminate access to newsgroups where child pornography is posted and purge their own servers of child porn Web sites.

The deal, announced on Thursday morning, follows agreements reached last month with Verizon, Sprint and Time Warner Cable.

The attorney general will also ramp up the pressure on more providers to sign on with a new Web site, nystopchildporn.com, where consumers can download letters to send to their providers “that have failed to make the same commitment to stop child porn,” according to a news release issued by Mr. Cuomo’s office.

The deals are significant, because newsgroups have been a somewhat forgotten corner of the Internet where child porn has flourished. But the agreements will only go so far in eliminating the scourge of child porn on the Web — it does not prevent customers from accessing Web sites on other servers not controlled by those companies.

“These agreements with two of the nation’s largest ISPs to eradicate child porn websites from their servers tighten the noose around this despicable trade,” Mr. Cuomo said in a statement. “I call on all ISPs to quickly adopt the reforms in our code of conduct.”

David Condit, AT&T’s senior vice president of state legislative and regulatory affairs, said in the statement:

We’re happy to work with Attorney General Cuomo’s office and the National Center for Missing and Exploited Children in the effort to help prevent the distribution of this harmful and abusive content.