The world’s first internet war is raging in Spain ahead of Sunday’s Catalan independence referendum, according to Julian Assange.

In a series of tweets on Saturday, Assange outlined how hundreds of websites have been censored by Spanish authorities, who have also suspended the use of 29 Catalan government apps relating to the referendum and occupied telecoms buildings.

The world's first internet war has begun, in Catalonia, as the people and government use it to organize an independence referendum on Sunday and Spanish intelligence attacks, freezing telecommunications links, occupying telecoms buildings, censors 100s of sites, protocols etc. — Julian Assange 🔹 (@JulianAssange) September 30, 2017

The official referendum website was just one of hundreds to be blocked. On September 20, Spain’s Guardia Civil raided the offices of the .cat domain registry in downtown Barcelona, seizing computers and arresting the registry’s IT manager.

What the Catalan govt's referendum site looks after censorship action from Madrid https://t.co/nFSCBEB1kuNow at: https://t.co/pyf7Kj2nHipic.twitter.com/GKx2AEw9sb — WikiLeaks (@wikileaks) September 14, 2017

The Guardia Civil blocks our website for the 2nd time. No notification, no court order, the GC disposes at its discretion. #holadictadurapic.twitter.com/Nc0aEoYrY6 — ANC International (@assemblea_int) September 27, 2017

The registry was established to provide an online space for Catalan language and culture and has over 100,000 active domain names. The raid came just days after the Spanish government ordered the registry take down all .cat domains used for the referendum.

On Friday, following a court ruling, Google blocked a Catalan government app that allowed users to check their polling stations. The following day police entered the headquarters of the Catalan government's Telecommunications and IT Center, known as CTTI.

Undeterred, Catalan authorities have issued instructions advising citizens to use proxies to circumvent restrictions put in place by internet service providers such as Movistar and Vodafone. Pirate bay co-founder, Peter Sunde, offered his assistance to the Catalan people and government via Twitter.

If you're running a Catalan site being shut down by Spanish authorities, contact me for anonymous hosting and domains. We've got you covered — Peter Sunde (@brokep) September 18, 2017

Many prominent internet activists and academics, including Edward Snowden and Noam Chomsky, have rallied to the Catalan cause in recent days.

One can be against Catalan independence and still in favor of human rights. But one cannot be in favor of Rajoy's crackdown and say the same — Edward Snowden (@Snowden) September 21, 2017

READ MORE: Echoes of Franco in Spain’s ‘political repression’ of Catalonia - 70 academics incl Chomsky

Assange has been a vocal supporter of the Catalan independence referendum, tweeting that the fate of Spanish Prime Minister Mariano Rajoy and his government “hangs in the balance over Catalonia.”

“What is happening in Catalonia in the most significant Western conflict between people and state since the fall of the Berlin wall,” Assange tweeted Saturday.

The fate of president Rajoy, PP (Spain's ruling party), Spain's security services and judiciary hangs in the balance over Catalonia. A shock wave is coming and no trick is too dirty, no lie is too bold and no escalation is too much for a deep state to save itself. Watch. — Julian Assange 🔹 (@JulianAssange) September 29, 2017

What is happening in Catalonia in the most significant Western conflict between people and state since the fall of the Berlin wall--but its methods are 2017, from VPNs, proxies, mirrors and encrypted chat to internet surveillance and censorship, bot propaganda and body armor. — Julian Assange 🔹 (@JulianAssange) September 30, 2017

Despite the Spanish government’s crackdown, Catalan separatists are determined to hold the referendum. Activists have occupied dozens of schools, intended to be used as polling stations, to stop police from shutting them down.

On September 6, Catalonia’s Parliament passed a bill paving the way for an independence referendum to be held on October 1. The Spanish government, however, insists the proposed referendum is illegal.