Iranian news agencies say Tehran's prosecutor has filed criminal charges against the "management" of Telegram, the popular encrypted messaging app founded by Russian social-networking mogul Pavel Durov.
Prosecutor Abbas Jafari Dolatabadi said that the charges stemmed from Telegram's alleged role as a platform for child pornography and extremist content, including by Islamic State militants.
The reports on September 26 by the semiofficial ISNA news agency and the judiciary's Mizan news agency did not name specific individuals implicated in the case.
Telegram, which Durov launched in 2013, is used by many Iranians for messaging as well as for exchanging news and information. Durov said in April that there were an estimated 40 million active users in Iran.
Iranian media outlets and many of the country's politicians maintain their own channels on Telegram, which has previously clashed with Iranian authorities.
Durov said on September 26 that he was surprised to learn of the reported charges and that he believes the "real reasons are different" than child pornography and extremism.
"We are actively blocking terrorist and pornographic content in Iran," Durov said on Twitter:
Iran has some of the world's toughest online censorship regulations, with tens of thousands of websites, including social media and news sites, filtered over content deemed sensitive or immoral.
ISNA cited Dolatabadi as saying that "Western law" did not apply in the Telegram case and that the matter had been handed to the international affairs department of the Tehran prosecutor's office.
It was not immediately clear whether Iran might seek to prosecute Durov.
The enigmatic founder of the popular Russian social-networking site VKontakte left Russia several years ago.
In March, Iranian authorities arrested 12 managers of popular reformist and pro-government Telegram channels -- a move some critics said was a crackdown ahead of the May presidential election.
Those arrests were criticized by President Hassan Rohani, who won a second term in office.