Iran has banned all government bodies from using foreign-based messaging apps, as Supreme Leader Ayatollah Ali Khamenei's office announced that his Telegram account would be shut down to protect national interests.
Iranian news agencies did not give a reason for the government ban on April 18, and it was not clear whether it applied to civil servants outside working hours.
The order comes days after a senior lawmaker said that the Telegram instant messaging app, thought to be used by an estimated 40 million users in the country, will be blocked by the end of April.
Other officials have said that no decision has been made about restricting the app.
The authorities temporarily shut down Telegram in January in an effort to contain antiestablishment protests across the country.
Khamenei's office said that it would cease using Telegram "in line with safeguarding national interests and removing the monopoly" of the messaging app.
It said that news and information about the supreme leader will be shared via three Iranian messengers.
Khamenei also has a presence on Twitter and Facebook, which are blocked in Iran.
President Hassan Rohani announced that he too was giving up Telegram. His account said the president's messages would continue through the "messaging applications of our country."
First Vice President Eshaq Jahangiri and Foreign Ministry spokesman Bahram Qasemi also closed their Telegram accounts, the official IRNA news agency reported.
In recent weeks, the authorities have been encouraging Iranians to join domestic alternatives to Telegram.
Iran's move comes after a court in Russia last week ordered Telegram, set up by Russian entrepreneur Pavel Durov, to be blocked after the company refused to share its encryption data with the country's security services.