France held the Russian-born founder of Telegram Pavel Durov in custody for a second day of questioning on Monday over alleged offences related to the popular but controversial messaging app, which insisted he had "nothing to hide". His arrest after flying into the Le Bourget airport outside Paris late Saturday is the latest extraordinary twist in the career of one of the world's most influential tech icons. The detention of Durov, 39, was extended beyond Sunday night by the investigating magistrate who is handling the case, according to a source close to the investigation.

This initial period of detention for questioning can last up to a maximum of 96 hours. When this phase of detention ends, the judge can then decide to free Durov, whose fortune is estimated by Forbes magazine at $15.5 billion, or press charges and remand him in further custody.

Russia has accused France of "refusing to cooperate" while fellow tech mogul Elon Musk swept to Durov's defence and called for his release. Durov holds a French passport in addition to other nationalities. Durov had arrived in Paris from Baku, Azerbaijan, and was planning to have dinner in the French capital, a source close to the case said.

He was accompanied by a bodyguard and a personal assistant who always accompany him, added the source, asking not to be named. France's OFMIN, an office tasked with preventing violence against minors, had issued an arrest warrant for Durov in a preliminary investigation into alleged offences inc.