French authorities detained Pavel Durov, the top executive of the online communications platform Telegram, on Saturday on charges related to the spread of illicit material on the service, according to French news media reports.

Mr. Durov, 39, a Russian-born entrepreneur, was reportedly arrested at Le Bourget airport near Paris after landing from Azerbaijan. His detention could not immediately be confirmed.

The Russian Embassy in France said in a statement on Sunday that it had asked the French authorities for clarification on news of the arrest.

Representatives of the French police and Interior Ministry declined to comment and redirected questions to the Paris prosecutor’s office. The Paris prosecutor’s office, citing an open investigation, also declined to comment.

Telegram did not respond to requests for comment.

Telegram, with more than 900 million users, has long been on the radar of law enforcement agencies around the world because terrorist organizations, drug runners, weapons dealers and far-right extremist groups have used it for communicating, recruiting and organizing.

National governments, especially in the European Union, have intensified pressure on companies to combat disinformation and online extremism. Telegram has operated with less moderation of content than other similar online platforms and does not always cooperate with the authorities.

Mr. Durov, whose net worth was estimated by Bloomberg at more than $9 billion, has largely avoided the kind of public scrutiny faced by top executives of other large online platforms, including Elon Musk of X, Mark Zuckerberg of Meta, Shou Chew of TikTok and Sundar Pichai of Google.

A Russian national, Mr. Durov left Russia in 2014 after he lost control of Vkontakte, the rival to Facebook in Russia. The year before, he founded Telegram, selling it as an uncensored and secretive way to communicate. The company is now based in Dubai, United Arab Emirates, and Mr. Durov has citizenship in France and the U.A.E., according to Telegram.