Reporters Without Borders said it had restored its website in Egypt on Friday, exactly one year after it was blocked by the authorities.
"Access to hundreds of websites are blocked in Egypt, placing journalists in a virtual jail," the press freedom body said on its site.
"To draw attention to this censorship, and to circumvent it, Reporters Without Borders (RSF) is making its own website accessible again in Egypt today."
More than 500 news and NGO sites are blocked in Egypt, according to the Cairo-based Association for the Freedom of Thought and Expression.
Around 100 news sites -- including Al Jazeera, Huffington Post Arabic and BuzzFeed -- were blocked last year, RSF said.
The sites of independent local news organisations have also been blocked.
Human rights groups regularly criticise moves by President Abdel Fattah al-Sisi's government to curtail free speech.
"Online censorship is one side of the oppressive system that the regime wants to extend in Egypt," said Elodie Vialle, the head of Reporters Without Borders' journalism and technology desk.
"It entails putting journalists 'on mute' in order to make it easier to spread pro-government content.
"The other side is that the technology is used to spy on them, which in some cases is sold by European companies," added Vialle.
RSF called on "democracies to condemn the Egyptian regime's closed, censored and monitored internet model".
Reporters Without Borders said it was unblocking its site through a website "mirroring" technique, which involves copying content and switching servers.
Egyptian authorities have not acknowledged or denied blocking certain sites.
In July, parliament passed a law reinforcing the state's control over the internet, including social media accounts of organisations and individuals with more than 5,000 followers.
Egypt is placed 161 out of 180 countries in RSF's press freedom rankings.
© 2018 AFP