BEIJING — Chinese bloggers using a new Microsoft service to post messages titled "democracy," "capitalism," "liberty" or "human rights" are greeted with a bright yellow warning.
"This message includes forbidden language," it scolds. "Please delete the prohibited expression."
The restrictions were agreed upon by Microsoft and its Chinese partner, the government-linked Shanghai Alliance Investment. The limits have sparked a debate here and in the online world about how free speech could be threatened when the world's most powerful software company forges an alliance with the largest Communist country.
Multinational companies from cigarette makers to baby formula companies routinely change their advertising and other corporate behavior to adapt to local laws. Experts say that Internet companies such as Microsoft are often the focus of controversy because their products are linked to free speech issues, and many rules governing blogs -- or Web logs -- and other electronic speech are evolving.
"There's a spectrum here," said Jonathan Zittrain, co-founder of Harvard's Berkman Center for Internet & Society and an author of a recent study on internet censorship in China. "It's one thing to provide a regime with steel, another to provide bullets, and another to serve as the executioner."
Executives with the Redmond, Wash.-based software giant argue that they are only following local laws and any disadvantage is outweighed by benefits users get from the company's services.
"Even with the filters, we're helping millions of people communicate, share stories, share photographs and build relationships," said Adam Sohn, Microsoft's global sales and marketing director. "For us, that is the key point here."
Microsoft adds that filtering objectionable words is nothing new. In the United States, the company blocks use of several words in titles, including "whore" and "pornography."
Yahoo and Google, two other large Internet firms, have also imposed limits on search results in France and Germany, where Nazi propaganda and memorabilia are banned.
In China, however, censorship is far more extensive. Computer users often find that filters on servers and search engines, including Yahoo's, prevent them from accessing pages, posting blogs or receiving e-mails on topics deemed sensitive by the Communist Party. Repeated violations can elicit a visit by police, leading in extreme cases to imprisonment on charges of threatening national security.
Human rights groups, including Reporters Without Borders, say Microsoft is sacrificing free speech principles in its headlong quest for profits and that the company should follow a higher standard.
"No one should break the law, but at the same time we all believe in universal values," said Julien Pain, head of the organization's Internet monitoring group. "If China required underage children to work, would you do it? Free speech is not an American value or a French value. It's a human value."
China has in recent months tightened its grip on the Internet and other media, as well as on scholars and others seen deviating from the Communist Party line. The nation's 150,000 journalists were recently instructed to attend a one-week ideology course, according to media reports. And last month, the government announced new rules requiring that all websites in China be registered.
The current debate raises questions about whether multinational companies have a duty to help promote political freedoms in a world where their power and global standing rival many governments'. Previous debates over corporate conduct have focused on environmental issues, fair wages and working conditions.
If international companies do not act roughly the same in various markets, they leave themselves exposed to charges of hypocrisy, said David Vidal, research director on global corporate citizenship at the Conference Board, a nonprofit group that advises management.
"It's obvious that the biggest test case of this will be China," he said.
Microsoft, along with many of its rivals, has made no secret of its keen interest in China's nearly 100 million Internet users -- a market second only to the United States' -- and a software industry that has grown 380% since 2000, according to government statistics.
Microsoft Chairman Bill Gates and Chief Executive Steve Ballmer repeatedly visited China in recent years, helping to strengthen the company's relationship with top leaders in a country where connections are often vital in securing deals. Microsoft's partner in the MSN China venture, Shanghai Alliance, is run by a son of former Chinese President Jiang Zemin.