Microsoft, Yahoo and Google have all refused invitations to Amnesty International's conference against internet censorship and repression.
Amnesty said in a statement that the "Chinese model" of internet repression, which involves blocking websites and arresting bloggers, is becoming popular around the world.
Amnesty is disappointed the trio will not be discussing their policies in public.
... "It would have been useful to have heard the arguments about why they behave as they do, and for them to hear the counter arguments, and how their activities are contrary to the business principles they describe - their belief in the internet being a forum for freedom of information. That's the platform that they've built their business on," said an Amnesty spokesman.
Only Google responded to the reporter's questions and only to justify their operations in China.