Amnesty International has called on the world's bloggers to stand up for freedom of expression on the internet.
The human rights organisation believes that fundamental rights, particularly freedom of expression and privacy, are under threat from governments that want to control what citizens say and what information they can access.
Amnesty's call comes as internet industry players prepare to gather at the Internet Governance Forum in Athens this week to discuss the future of the internet.
The organisation's action coincides with an appeal on behalf of a blogger in Iran who was detained earlier this month. Kianoosh Sanjari was arrested while reporting on clashes between security forces and supporters of Shia cleric Ayatollah Boroujerdi.
Amnesty International fears that Sanjari may be at risk of torture or ill-treatment.
Steve Ballinger, a member of Amnesty International's delegation to the Internet Governance Forum, said: "Freedom of expression online is a right, not a privilege. But it's a right that needs defending.
"We are asking bloggers worldwide to show their solidarity with web users in countries where they can face jail just for criticising the government.
"The Internet Governance Forum needs to know that the online community is bothered about free expression online and is willing to stand up for it."
Amnesty International believes that the internet is a powerful force for human rights which enables the free flow of ideas and information around the world, but that some governments have sought to curtail this freedom.
"People have been locked up just for expressing their views in an email or a website. Sites and blogs have been shut down and firewalls built to prevent access to information," said Ballinger.
"Companies have restricted internet searches to stop people accessing information that repressive governments do not want them to see."
The Internet Governance Forum runs from 30 October to 2 November at the Divani Apollon Palace & Spa Hotel in Athens.
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