"It will switch from being an information gateway to an information gatekeeper.''
He said Human Rights Watch wrote Yahoo! CEO Terry Semel on July 30 asking for a meeting to express "deep concern'' and discuss free expression issues in China. Yahoo! has not yet responded, Roth said.
"If a powerful industry leader such as Yahoo! submits so readily to official censorship requests, it sells short the potential of this new medium to break Beijing's grasp on the free flow of information,'' Roth said in a statement.
Telephone and e-mail messages left with Yahoo! spokeswoman Diana Lee at the portal's Sunnyvale, California, headquarters after business hours Friday were not immediately returned.
The company's Beijing office confirmed last month that it signed the pledge. In the United States, Yahoo!, one of the Internet's most comprehensive catalogs of Web sites, has cultivated an image of anarchic creativity and Internet freedom. Originally, the site's name was an acronym for "Yet Another Hierarchical Officious Oracle.''
The "Public Pledge on Self-discipline for China Internet Industry'' has attracted more than 300 signatories since its launch March 16, according to the Internet Society of China, which organized it.
The pledge identifies its main aims as promotion of Internet use, prevention of online crime, fostering healthy industry competition, avoiding intellectual property violations.
Other clauses, though, speak to China's tight control over information and the government's extreme sensitivity to criticism or political challenges. New regulations on Internet publishing took effect Aug. 1 "to promote the healthy development of Internet publications.''
Those who sign the pledge must refrain from "producing, posting or disseminating pernicious information that may jeopardize state security and disrupt social stability.''
The prohibition also covers information that breaks laws and spreads "superstition and obscenity.''
Members must remove material deemed offensive or face expulsion from the group.
Signers also pledge to monitor content of foreign-based Web sites and block those containing unspecified harmful information.
"We understand that Yahoo! is obliged to abide by laws in countries where it does business,'' Roth's letter to Yahoo!'s Semel said.
"But Yahoo! should make it a point to do everything in its power to avoid affirmatively endorsing insidious censorship practices.''
China has aggressively promoted the Internet for commercial purposes. As of April, China had more than 38 million Internet users and nearly 280,000 Web sites, according to the government's Xinhua News Agency.
China has also closed thousands of Internet cafes since a fire June 16 at a Beijing cafe killed 25 people.
Such cafes are the main route to the Web for millions of Chinese who do not own computers, and Roth said they should not face punishment for the sites they visit.
"Voluntary codes of corporate conduct upholding human rights standards have become increasingly commonplace in old economy industries such as apparel, footwear, and even oil and gas,'' he said.
"It is ironic that a 'new economy' company would sign on to what is in effect a code of misconduct that would undermine human rights.'' -