Microsoft is refusing to say what laws blogger Zhoa Jing broke that caused it to remove his entries from the MSN server.
The company did, however, confirm that the blogger used an msn.com URL rather than msn.com.cn, which is reserved for Chinese servers run by Microsoft and a Chinese partner.
"I do not know where the physical server is located, but it would appear that Microsoft is permitting the Chinese authorities to exert control over content stored outside China," said Daniel Simons, legal officer at free expression advocacy group Article 19.
"If Microsoft is going to bow to the lowest common denominator and allow every country in which it does business to control the content of all their blogging servers worldwide, taking down content will soon become a full-time occupation."
Microsoft is sticking to its statement that "the MSN Space has been blocked to help ensure that the service complies with local laws in China". However, it will not say what, if any, laws have been broken.
Article 35 in the Chinese constitution states: "Citizens of the People's Republic of China enjoy freedom of speech, of the press, of assembly, of association, of procession and of demonstration."
It also states: "Citizens of the People's Republic of China have the right to criticize and make suggestions to any state organ or functionary. No one may suppress such complaints, charges and exposures, or retaliate against the citizens making them."
The situation has been hotly debated by Microsoft employees on their own blogs. "I do think that Microsoft should make more details available," wrote Microsoft employee Alfred Thompson on his personal blog.
"I think that would put more pressure on who ever forced them to do what they did to explain themselves. But they probably will not because that would take some courage and put people at risk."
Meanwhile fellow Microsoft employee Robert Scoble, who had previously accused MSN of acting like "thugs", has toned down the criticism of his employer.
"I have been talking to lots of people today, inside and outside Microsoft," he wrote. "In every instance they asked me to keep those conversations confidential. Why? Cause we’re talking about international relations here and the lives of employees.
"It's real easy as Americans to rattle the door and ask for change, but we don't live there."
Microsoft comes up with a new way to foist its unloved and little used Edge web browser on people
Facebook suspends Cambridge Analytica following weekend claims that it illegally harvested information from 50 million users
Insider claims Cambridge Analytica used academic app to filch Facebook data of 50 million users
Is the Samsung Galaxy S9+ worth its high price?