The Italian language Wikipedia website has 'gone dark' in a protest against proposed EU copyright laws, with all pages temporarily blocked.
MEPs will this week vote on a new copyright directive, which was previously approved by a committee.
EU politicians say the proposed measures are aimed at achieving goals such as "fair pay for artists and journalists" and "protecting freedom of expression and innovation".
However, activists and web freedom organisations have voiced strong opposition to the proposals.
Two articles in particular - 11 and 13 - have caused significant controversy.
Campaigners claim the rules would effectively ban memes from the web.
The European Digital Rights (EDRi) association claims the directive contains measures "to monitor and filter virtually all uploads to the internet".
Amid mounting opposition to the proposals, the Italian Wikipedia community has decided to 'obscure all encyclopedia pages' to highlight its concerns around the proposed copyright rules.
They write: "The directive instead of updating the copyright laws in Europe and promoting the participation of all the citizens to the society of information, threatens online freedom and creates obstacles to accessing the Web, imposing new barriers, filters and restrictions.
"If the proposal would be approved in its current form, it could be impossible to share a news article on social networks, or find it through a search engine; Wikipedia itself would be at risk."
It adds: "We want to continue to offer a free, open, collaborative encyclopedia with verifiable content. We call on all Members of the European Parliament to vote against the current text [and] reopen the discussion."
If the vote on the directive passes this week, the controversial law will be negotiated with the European Council ahead of a potential final vote later this year.