The social media network and encrypted messaging app is one of the most downloaded apps in the world.

But who is the man behind it - and how does the app work?

'Russia's Mark Zuckerberg'

Born in Russia, Pavel Durov is the founder and owner of Telegram - a free-to-use messaging app that competes with other platforms such as WhatsApp, Facebook Messenger and TikTok.

His fortune is currently estimated by Forbes at $15.5bn (£11.7bn) - making him the 120th richest person in the world - and he is sometimes dubbed "Russia's Mark Zuckerberg".

The 39-year-old left the country in 2014, a year after Telegram was launched, after refusing to comply with demands by the Russian government to shut down opposition communities on VKontakte (VK) - an earlier social media platform he founded with his brother, and later sold.

He moved to Dubai in 2017 and became a French citizen in August 2021.

According to media reports, Durov is also a citizen of the United Arab Emirates as well as St Kitts and Nevis, a dual-island nation in the Caribbean.

Telegram's popularity has led to rise in scrutiny

The Telegram app is influential in Russia, Ukraine and former Soviet republics.

However, Russia began blocking the app in 2018 after the company refused to comply with a court order to grant state security services access to its users' encrypted messages. The action had little effect on the availability of Telegram there, but did spark mass protests in Moscow and criticism from non-governmental organisations (NGOs).

The app is becoming increasingly popular, and is now among the top five most downloaded around the world, the company says. In 2023, it passed 700 million active monthly users - and the aim is to surpass 1 billion within a year.

However, its growing popularity has led to increased scrutiny from several countries in Europe, including France, on potential security and data breach concerns.

"Telegram is committed to protecting user privacy and human rights such as freedom of speech and assembly," the company says on its website.

"It has played a prominent role in pro-democracy movements around the world, including in Iran, Russia, Belarus, Myanmar and Hong Kong."

Mr Durov is also a sperm donor who has helped more than 100 couples in 12 countries to have children.

He is known for often dressing in black clothing, in a look similar to the character Neo from the sci-fi Matrix film series.

Following his arrest, several activists gathered in Russia's capital to show their support. Paper planes - referring to Telegram's logo - were placed near the French embassy in Moscow.

Speaking to controversial US media personality Tucker Carlson in April, Mr Durov talked about leaving Russia, saying he would "rather be free than to take orders from anyone".