MOSCOW — He is described as the Russian equivalent of Facebook founder Mark Zuckerberg. After launching VKontakte, Russia's biggest social network, a decade ago, Pavel Durov has more recently become one of President Vladimir Putin's fiercest, if ever discreet, opponents.

Forced into exile after quarrels with the Kremlin, he is never where you'd expect him to be.

Many had expected to see him at the opening of Moscow's Internet Economy Forum in December 2015. But Durov, who also founded controversial messaging application Telegram, didn't show up. "No surprise. He's out of the system," was the message from several attendees, each younger and more laid-back than the next. They say that Durov no longer wants his own image associated with Russia, preferring instead to emphasize that his vision and projects are global in nature.

Since Durov's power struggle with Russian authorities in 2014 over VKontakte, which was eventually acquired by businessmen with links to the Kremlin for what is estimated to be between $50 and $100 million, the now 31-year-old is officially in exile. And yet, he returns to Saint Petersburg regularly to visit family. Few have managed to see Durov in his hometown where, in 2006, he created the social network after studying at university. You're better off looking for him in Barcelona or San Francisco.

The best way to contact "Pasha", as Durov is called, is through the Internet using one of the many social network platforms, messaging services and email addresses he uses. We tried with two months of repeated attempts, but failed.

"Pasha only replies when it suits him, and when he has time. He's a pioneer in his field, he's aware of his influence — the influence of a successful entrepreneur who became a media mogul in his own right," said Pavel Kushelev, a Russian webspace expert, showing the last message he got from Durov on his phone. It was just after the Nov. 13, 2015, attacks in Paris when Telegram, the messaging app Durov launched with brother Nikolai, was accused of being used by militants to help organize the terror attack.

Telegram was conceived of to protect users from government control thanks to a stronger encryption system than rival messaging application Whatsapp. That's why it became a formidable tool for terrorists.

Durov responded to criticism by blocking 78 accounts linked to the Islamic State (ISIS), the jihadist group that claimed responsibility for the attacks. Before the Paris attacks, critics in Russia had called for Telegram and other messaging services to be banned. "You might as well ban words," Durov retorted.

But critics persisted. Some say that people at Telegram were aware long before the Paris attacks that jihadists were using the service. "From the moment it was born, some 90,000 people a day downloaded the app in the Middle East," said Internet expert Igor Achmanov.

"It's huge. This can't have gone unnoticed. The fact that there were people from (ISIS) among the users came out very quickly," he said. "But it wasn't until after the Paris attacks that Pavel Durov decided to block accounts."

A well-known figure in Russia, Achmanov has worked personally with Durov, when the VKontakte founder needed connections to develop his service. "A young man with a strange behavior," Achmanov said of Durov. "The king of weird stuff. He actually fell out with a lot of people."

Achmanov remembers one time when Durov threw 5,000-ruble bills (about $140 at the time) folded like paper planes from his office window in Saint Petersburg, and laughed as he watched passersby. "He's a savage," Achmanov said. "He has this young nouveau-riche's mentality, of people who don't think about what they do, but then get scared by the consequences of their actions."

This is probably what happened after the Paris attacks when Durov spoke about French authorities. "The French government is as responsible as the Islamic State for this because it is their policies and carelessness that eventually led to the tragedy," he wrote on Instagram. "They take money away from hardworking people of France with outrageously high taxes and spend them on waging useless wars in the Middle East and on creating a parasitic social paradise for North African immigrants."

Durov, who now spends most of his time in the comfort of Western countries, worried about the criticism of his comments at a time when he's trying to grow Telegram's business. Since his remarks on the French government, Durov has kept quiet.

"He's first and foremost an introvert," said Matvei Alekseev, a former VKontakte employee. Durov is single and often dresses in black. "It's difficult to work with him. He doesn't speak much."

Alekseev doesn't hide his admiration for Durov, who is considered an "Internet Robin Hood" for placing civil liberties above all else in an authoritarian country. Durov ultimately decided to leave Russia in order to defend his freedom as an entrepreneur. "Unfortunately, the country is incompatible with internet business at the moment," he said at the time, after being forced to give away financial control of VKontakte to pro-Kremlin businessmen.

"I publicly refused to cooperate with the authorities. They can't stand me," Durov said just before leaving.

Russia believed the social network had played a crucial role in the pro-European protests in Ukraine, and Russian intelligence FSB wanted to collect data on the movement's leaders after they had used the service to rally demonstrators.

With few words, a sensational resignation and a sudden exile, Durov became, in spite of himself, the symbol of Kremlin's takeover of Russian internet. Cases of censorship have multiplied between 2014 and 2015, according to a report by Agora human rights associations, a network of lawyers. In December, a blogger form Siberia was sentenced to five years in a labor camp, and a three-year ban from the Internet, for publishing pro-Ukrainian videos.

Before Durov's exile, the Russian parliament passed a new law enforcing strict rules for blogs. Under the new legislation, any site that gets more than 3,000 views a day must register with a media watchdog and to commit to verifying the information it publishes.

These court proceedings and regulations are the exact opposite of the freedom of speech defended by Durov, who had refused to hand over the personal data of Russian opponents to the FSB and declined to block the web page of Alexei Navalny, one of the leaders of the anti-Kremlin opposition.

With VKontakte, Durov wanted to give everyone, especially the underprivileged, free access to what only the elite had enjoyed. With Telegram, he intends to defend the individual's right to privacy. Durov isn't just a rebel. He's a die-hard libertarian.