PARIS — A French investigative judge extended police custody for the CEO of the popular messaging app Telegram, Pavel Durov, prosecutors said on Tuesday.

Durov was detained Saturday at Le Bourget airport as part of a judicial inquiry opened last month involving 12 alleged criminal violations. They include complicity in selling child sexual abuse material and in drug trafficking, fraud, abetting organized crime transactions and refusing to share information or documents with investigators when required by law.

A statement from the Paris prosecutor’s office said Durov’s police custody order was extended on Monday evening for up to 48 hours. After that, authorities must release or charge him, the prosecutor’s office said in an earlier statement.

Durov is a citizen of Russia, France, the United Arab Emirates and the Caribbean island nation of St. Kitts and Nevis.

Russian government officials have expressed outrage at his detention, with some calling it politically motivated and proof of the West’s double standard on freedom of speech. The outcry has raised eyebrows among Kremlin critics because in 2018, Russian authorities themselves tried to block Telegram but failed, withdrawing the ban in 2020.

On Tuesday, Kremlin spokesman Dmitry Peskov said the allegations against Durov were “very serious” and emphasized that “they require evidence that is just as serious” to quash suspicions his arrest was politically motivated.

Without substantial evidence, “we are witnessing a direct attempt to restrict freedom of communication and, one might even say, direct intimidation of the head of a large company,” Peskov said during his regular media conference call.

French President Emmanuel Macron said Monday that Durov’s arrest wasn’t a political move but part of an independent investigation. Macron posted on X that his country “is deeply committed” to freedom of expression but “freedoms are upheld within a legal framework, both on social media and in real life, to protect citizens and respect their fundamental rights.”

The UAE Foreign Ministry said Tuesday that it was “closely following the case” and had asked France to provide Durov “with all the necessary consular services in an urgent manner.”

Peskov said he hoped that Durov “has all the necessary opportunities for his legal defense” and added that Moscow stands “ready to provide all necessary assistance and support” to the Telegram CEO as a Russian citizen.

“But the situation is complicated by the fact that he is also a citizen of France,” Peskov said.

Iran’s supreme leader, Ayatollah Ali Khamenei, also weighed in on Durov’s arrest.

“You saw that France arrested this poor young fellow, yes, they are that strict,” Khamenei said on Tuesday during a meeting with members of new reformist President Masoud Pezeshkian’s Cabinet.

“That’s because he has violated their governance (over the internet),” Khamenei said. “Violating the governance is not acceptable. You rule a country, you have a responsibility … you can’t let anyone violate your governance.”

Telegram is banned in Iran after years of protests challenging the country’s Shiite theocracy, though the app remains widely used by Iranians.

In Geneva, Ravina Shamdasani, a spokesperson for the U.N. human rights office, said it was seeking more information about Durov’s case from French authorities.

“At this stage of the investigation, we just don’t have enough information and it would really be too early for us to weigh in.”

Telegram, which says it has nearly a billion users worldwide, was founded by Durov and his brother after he himself faced pressure from the Russian authorities.

In 2013, he sold his stake in VKontakte, a popular Russian social networking site which he launched in 2006.

The company came under pressure during the Russian government’s crackdown following mass pro-democracy protests that rocked Moscow at the end of 2011 and 2012.

Durov had said the authorities demanded that the site take down online communities of Russian opposition activists, and later that it hand over personal data of users who took part in the 2013-2014 popular uprising in Ukraine, which eventually ousted a pro-Kremlin president.

Durov said in a recent interview that he had turned down these demands and left the country.

The demonstrations prompted Russian authorities to clamp down on the digital space, and Telegram and its pro-privacy rhetoric offered a convenient way for Russians to communicate and share news.

Telegram also continues to be a popular source of news in Ukraine, where both media outlets and officials use it to share information on the war, and deliver missile and air raid alerts.

In a statement posted on its platform after his arrest, Telegram said it abides by EU laws, and its moderation is “within industry standards and constantly improving.”

“It is absurd to claim that a platform or its owner are responsible for abuse of that platform,” Telegram’s post said. “Almost a billion users globally use Telegram as means of communication and as a source of vital information. We’re awaiting a prompt resolution of this situation. Telegram is with you all.”

Western governments have often criticized Telegram for a lack of content moderation, which experts say opens up the messaging platform for potential use in money laundering, drug trafficking and the sharing of material linked to the sexual exploitation of minors.

In 2022, Germany issued fines of $5 million against Telegram’s operators for failing to establish a lawful way to reporting illegal content or to name an entity in Germany to receive official communication. Both are required under German laws that regulate large online platforms.