A list of 13 "enemies of the Internet" has been released by human rights group Reporters Without Borders (RSF).
For the first time, Egypt has been added to the list while Nepal, Libya and the Maldives have all been removed.
The list consists of countries that RSF believes are suppressing freedom of expression on the Internet.
The civil liberties pressure group has organised a 24-hour protest, inviting web users to vote for the worst offending countries.
Visitors to the RSF website are also invited to leave a voice message for Yahoo's co-founder Jerry Yang, expressing their views on the firm's involvement in China.
RSF has been outspoken in its condemnation of Yahoo. The search engine has been criticised along with other companies for helping the Chinese authorities block access to some online material.
The blacklist is published annually but it is the first time RSF has organised an online protest to accompany the list.
"We wanted to mobilise net users so that when we lobby certain countries we can say that the concerns are not just ours but those of thousands of Internet users around the world," said a spokesman for RSF.
Many of those on the Internet blacklist are countries that are regularly criticised by human rights groups, such as China and Burma.
Egypt is a new entrant and has been shortlisted for its attitude to bloggers rather than specific web censorship, said RSF.
"Three bloggers have been arrested and detained this year for speaking out in favour of democratic reform. This is an appeal to the Egyptian government to change its position," said the RSF spokesman.
"The fact that this year we have removed three countries from the list is encouraging. It shows that the situation can change for the better," he added.
On a visit to Libya, Reporters Without Borders found that the Libyan Internet was no longer censored although it still considers President Maummar Gaddafi to be a "predator of press freedom".
THE 13 COUNTRIES BLACKLISTED
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