Catalan authorities have accused the Spanish government blocking websites aimed to spread information about the region’s independence referendum.

The move is part of a crackdown on the Catalan independence movement to prevent the vote, which includes the confiscation of ballot papers and the deployment of extra police officers to Catalonia.

Separatists hope the referendum will go ahead on 1 October to decide whether Catalonia, an autonomous region of northeastern Spain, should declare itself an independent country.

The Spanish government has insisted the referendum is illegal and is taking action to stop it, including the spreading of information seen to promote the vote.

Earlier this week, police summoned 17 people for questioning over the development of web platforms related to the referendum.

A police spokesperson told AFP the people were suspected of “disseminating a website for people to participate in a referendum declared illegal by the constitutional court”.

An organisation which manages how users find websites with the extension .cat was raided by the Spanish police force, Politico reported.

The .cat Foundation, which manages the register of domains ending in .cat, was forced by authorities to block websites with information about the referendum.

The raid came shortly after a Spanish court ordered the foundation block websites related to the vote.

The homepage of the site Referendum.cat now displays a message stating: “This domain name has been seized pursuant to a seizure warrant under the Judicial Authority and is under its administration.”

A spokesperson for the Catalan government told the Guardian the move was denying people the right to freedom of information online.

Catalonia referendum protests – in pictures Show all 10 1 /10 Catalonia referendum protests – in pictures Catalonia referendum protests – in pictures Demonstrators block a Guardia Civil vehicle as they try to leave the Department of External Affairs, Institutional Relations and Transparency of the Catalan Government office in Barcelona AP/Emilio Morenatti Catalonia referendum protests – in pictures Demonstrators react as they try to stop the car carrying Xavier Puig, a senior at the Department of External Affairs, Institutional Relations and Transparency of the Catalan Government office, after he was arrested by Guardia Civil officers in Barcelona AP/Emilio Morenatti Catalonia referendum protests – in pictures A demonstrator reacts as he tries with others to stop the car carrying Xavier Puig, a senior at the Department of External Affairs, Institutional Relations and Transparency of the Catalan Government office, after he was arrested by Guardia Civil officers in Barcelona AP/Emilio Morenatti Catalonia referendum protests – in pictures Spokeswoman of the Catalan pro-independence anticapitalist party "Candidatura d'Unitat Popular - CUP" (Popular Unity Candidacy), Ana Gabriel, talks to the media in Barcelona Josep Lago/AFP Catalonia referendum protests – in pictures Republican Left of Catalonia party's (ERC) Member of Parliament Joan Tarda (C) attends a demonstration outside the regional Economy Ministry in Catalonia during a police search for documents connected with the organisation of the Catalan independence referendum, in Barcelona EPA/Alejandro Garcia Catalonia referendum protests – in pictures A man holds pro-referendum poster next to a Spanish Civil Guard who stands in front of the Economy headquarters of Catalonia's regional government in Barcelona. The operation comes amid mounting tensions as Catalan leaders press ahead with preparations for an independence referendum on October 1 despite Madrid's ban and a court ruling deeming it illegal Josep Lago/AFP Catalonia referendum protests – in pictures People hold placards reading "Democracy" as they protest in front of the Economy headquarters of Catalonia's regional government in Barcelona AFP Catalonia referendum protests – in pictures A crowd of protesters gather outside the Catalan region's economy ministry after junior economy minister Josep Maria Jove was arrested by Spanish police during a raid on several government offices, in Barcelona Reuters/Albert Gea Catalonia referendum protests – in pictures People holding 'Esteladas' (Catalan pro-independence flags) attend a protest near the Economy headquarters of Catalonia's regional government Lluis Gene/AFP Catalonia referendum protests – in pictures People demonstrate on a Spanish Civil Guard Police car outside the Catalan Vice-President and Economy office as police officers holds a searching operation inside David Ramos/Getty Images

“What they’re doing by blocking domain name servers is doing what Turkey does and what China does and what North Korea does,” they said.