SHANGHAI, China — A human-rights group sued Yahoo this week, accusing the Internet giant of abetting the torture of pro-democracy writers by releasing data that allowed China’s government to identify them.

The suit, filed in U.S. District Court in San Francisco, says the company was complicit in the arrests of 57-year-old Wang Xiaoning and other Chinese Internet activists. The suit is the latest development in a campaign by advocacy groups to spotlight the conduct of American companies in China.

As they seek a slice of the booming Chinese market, Yahoo and other American companies have sometimes set aside core American values, such as free speech, to comply with the communist government’s laws.

The suit, in trying to hold Yahoo accountable, could become an important test case. Advocacy groups are seeking to use a 217-year-old U.S. law to punish corporations for human-rights violations abroad, an effort the Bush administration has opposed.

In 2003, Mr. Wang began serving a 10-year sentence on charges that he incited subversion with online treatises criticizing the government. He is named as a plaintiff in the Yahoo suit, which was filed with help from the World Organization for Human Rights USA, based in Washington.

Yahoo is guilty of “an act of corporate irresponsibility,” said Morton Sklar, executive director of the group. “Yahoo had reason to know that if they provided China with identification information that those individuals would be arrested.”

Mr. Wang’s wife, Yu Ling, said her husband is imprisoned in a labor camp and has been subjected to beatings. In an interview in Washington, she said through an interpreter that American technology companies such as Yahoo should be held to a high standard in their overseas conduct. She said Yahoo gave the Chinese government personal information tied to e-mail accounts that Mr. Wang used to distribute his writings,

The suit says that in 2001, Mr. Wang was using a Yahoo e-mail account to post anonymous writings to an Internet mailing list. The suit alleges that Yahoo, under pressure from the Chinese government, blocked that account. Mr. Wang set up a new account via Yahoo and began sending material again; the suit alleges that Yahoo gave the government information that allowed it to identify and arrest Mr. Wang in September 2002. The suit says prosecutors in the Chinese courts cited Yahoo’s cooperation.

Jim Cullinan, a spokesman for Yahoo, of Sunnyvale, Calif., said he could not comment on the suit or the specifics of Mr. Wang’s case because he had not seen the papers Wednesday afternoon. But he said Yahoo condemns the suppression of speech.

Companies that do business in other countries have to follow the laws of that country or their employees could be subject to penalties, he said. In addition, governments are not required to tell a company why they want information.

“No company would know if it is for a legitimate criminal investigation, or if it’s a matter of public safety, or it’s being used to prosecute political dissidents,” Mr. Cullinan said. Yahoo’s stance infuriates Ms. Yu, Mr. Wang’s wife.

“The Yahoo company didn’t even say ‘sorry,’ ” she said. “They think they haven’t done anything wrong.”

There were hopes in China that President Hu would loosen strict controls over the flow of information, but the opposite has happened. The Internet is heavily censored. Across the country, Internet cafes are being shuttered. Last month, Caijing, a business magazine, was pulled off newsstands because it contained information about a sensitive private-property law.