Spain has accused Pavel Durov of “spreading lies” and seeking to undermine democratic institutions after the Telegram founder used the messaging app to attack government plans to introduce a social media ban for under-16s and to hold tech companies responsible for hateful and harmful content.

Durov’s extraordinary public intervention – which came a day after Elon Musk called Spain’s prime minister, Pedro Sánchez, a “true fascist totalitarian” over the proposed measures – reveals the rapidly escalating tensions between European governments and powerful global technology chiefs.

In a blanket message sent to all Telegram users in Spain on Wednesday afternoon, the Russian technology entrepreneur accused Sánchez’s government of “pushing dangerous new regulations that threaten your internet freedoms”, adding that the measures could turn Spain “into a surveillance state under the guise of ‘protection’”.

Durov claimed the mandatory age verification contained in the proposed legislation would set a precedent for tracking “EVERY user’s identity, eroding anonymity and opening doors to mass data collection”. He also said that holding tech executives liable for illegal, hateful or harmful content would encourage “over-censorship” and lead platforms to “delete anything remotely controversial to avoid risks, silencing political dissent, journalism, and everyday opinions”.

Spanish government sources hit back, saying Durov’s unprecedented message to millions of users was designed to erode trust in institutions and demonstrated the need for social media and mobile messaging apps to be regulated.

“Telegram founder Pavel Durov used his unrestricted control of the app to send a mass message to all users in Spain, spreading several lies and making illegitimate attacks against the government. This is the first time this has happened in our country’s history,” they said.

“Spaniards cannot live in a world where foreign tech oligarchs can flood our phones with propaganda at will simply because the government has announced measures to protect minors and enforce the law.”

Durov was arrested in Paris in August 2024 as part of an inquiry into allegations of fraud, drug trafficking, organised crime, promotion of terrorism and cyberbullying. He was detained on suspicion of failing to take action to curb the allegedly criminal use of his platform and was eventually charged with 12 offences. He was later released under judicial supervision and has denied all the charges against him, describing his arrest as “legally and logically absurd” and saying investigators were “struggling to find anything that I or Telegram did wrong”.

Following the arrest, Telegram released a statement saying its chief executive “had nothing to hide” and that it was “absurd to claim that a platform or its owner are responsible for abuse of that platform”.

The Spanish government statement released on Wednesday said Durov had “deliberately designed a minimal moderation architecture that has turned Telegram into a recurring space for documented criminal activities such as child sex trafficking and drug trafficking”, with cases under investigation in Spain, France and South Korea.

On Tuesday, French prosecutors raided the French headquarters of Musk’s social media platform, X, and summoned him and the company’s former chief executive for questioning as part of an investigation into alleged cybercrime.

The investigation, launched in January last year, is examining alleged offences including complicity in the possession and organised distribution of child abuse images, violation of image rights through sexualised deepfakes and denial of crimes against humanity.

In a statement issued after the raid, X said: “The allegations underlying today’s raid are baseless and X categorically denies any wrongdoing. Today’s staged raid reinforces our conviction that this investigation distorts French law, circumvents due process, and endangers free speech.”

Growing anxieties over the harmful effects of social media have led a number of governments, including Spain, Britain, Greece and France, to adopt or consider the adoption of more stringent legislation. In December, Australia became the first country to ban children under 16 from such platforms.

Concern and anger over the tech barons’ propensity to interfere in domestic politics is increasingly prompting some European governments to swap the traditional codes of diplomatic politesse for humour, memes, rebuttal and ridicule – all on social media.

The French foreign ministry launched its @FrenchResponse account late last year, reflecting its belief that in a hostile online information environment it is both willing and able to deploy the billionaires’ own tools and language against them.

“Protecting children online is only ‘controversial’ for those who profit from not doing it. Everyone else agrees,” @FrenchResponse replied on X to Durov’s claim that Europe was “weaponising child protection to legitimise censorship and mass surveillance”.

The @FrenchResponse account first made a splash on 11 January, quote-replying to a post from Musk that asked “Why is the UK government so fascist?” with a photo of the X owner making what resembled a Nazi salute during Donald Trump’s inauguration.

The French foreign minister, Jean-Noël Barrot, praised the account’s strategy last month, saying: “The only right attitude, in the information war that has begun, is to raise our voice and to turn up the volume.”

Sánchez has used X to push back at the platform’s owner, who is also chief executive of SpaceX. After Musk appeared to take issue with Spain’s recent plan to regularise 500,000 undocumented migrants and asylum seekers, the prime minister replied: “Mars can wait. Humanity can’t.”

On Wednesday evening, he adapted a celebrated, if apocryphal, line from Don Quixote to respond to the barbs of Musk and Durov. The phrase – “Let the dogs bark, Sancho, it means we’re on track” – is used to suggest that shouts of disapproval and discouragement mean you’re doing something right. Sánchez repurposed it as: “Let the tech-oligarchs bark, Sancho, it means we’re on track.”

Worries over the primacy and ubiquity of US tech products have led some European countries to roll out plans to reduce their use of some well-known digital services. Last week, the French government announced 2.5 million civil servants would stop using US video-conferencing tools – including Zoom, Microsoft Teams, Webex and GoTo Meeting – and would switch to Visio, a homegrown service, by 2027.

The French civil service minister David Amiel said the aim was “to put an end to the use of non-European solutions, to guarantee the security and confidentiality of public electronic communications by relying on a powerful and sovereign tool”.

Meanwhile, Denmark’s government and the cities of Copenhagen and Aarhus have been trying out open-source software. “We must never make ourselves so dependent on so few that we can no longer act freely,” the digital minister, Caroline Stage Olsen, wrote on LinkedIn last year. “Too much public digital infrastructure is currently tied up with very few foreign suppliers.”

The Associated Press contributed to this report