Rights groups called on Google, Yahoo! and Microsoft on Friday not to censor their Web search engines one day this week to help protest cyber censorship.
"World Day Against Cyber Censorship is a day to advance and celebrate a free Internet as an open window to the world and denounce the attacks made on the free flow of information online," Reporters Without Borders and Amnesty International said in a letter to the tech giants.
"In the spirit of fostering freedom of expression, we are asking that you do not censor any of your search engines or blog platforms anywhere around the world on this day," they said.
"We urge you, on March 12th, to champion the vision of the Internet as a free space for everyone, regardless of nationality or geographic location, and fulfill the idea of a truly worldwide Web – even if just for one day.
"This would send a strong message to all "netizens" – individuals, organisations and states alike – that censorship online is not the only way forward," they said.
RSF and Amnesty said that currently, "there are more than two dozen countries restricting Internet access on a regular basis."
They said they "understand the challenges of operating in countries that restrict Internet access; these countries are trying to pressure you to obey local laws that do not comport with international law and standards that protect freedom of expression.
"But complying with local demands that violate international law does not justify your actions," they said.
"Your assistance allows states, such as China, to out-right ban access to information on ‘human rights,’ ‘dalai lama,’ ‘Charter 08’ or ‘democracy,’ as well as to respected human rights websites."
China exercises strict control over the Internet, blocking sites linked to Chinese dissidents, the outlawed Falun Gong spiritual movement, the Tibetan government-in-exile and those with information on the 1989 Tiananmen massacre.
A number of US companies, including Google, Yahoo!, Microsoft and Cisco, have been hauled before the US Congress in recent years and accused of complicity in building what has been called the "Great Firewall of China."
Google has been criticised for complying with Chinese government’s demands to filter Internet searches to eliminate query results regarding topics such as democracy or Tiananmen Square.
RSF staged the first "World Day Against Cyber Censorship" last year and plans to mark the day with a report on the state of Internet freedom worldwide.