The Iranian government has called on the messaging app Telegram to block "terrorist channels" in an effort to quell protests, according to the state-run media outlet IRIB.
"If [the] Telegram manager does not respect Iranians' demand, the application will be closed completely," Iran's Minister of Communications and Information Technology, Mohammad-Javad Azari Jahromi said on Wednesday.
A temporary block on Telegram was first imposed on Sunday after anti-government protests throughout the country. Telegram removed at least one opposition channel citing calls for violence, but CEO Pavel Durov has refused to shut down other channels he has called peaceful.
In a Telegram post, Durov said, "We are proud that Telegram is used by thousands of massive opposition channels all over the world. We consider freedom of speech an undeniable human right, and would rather get blocked in a country by its authorities than limit peaceful expression of alternative opinions." On Tuesday, in a Twitter post, Durov added that the popular messaging app Whatsapp was still "fully accessible" in Iran.
There are over 47 million active social media users in Iran, with Telegram and the Facebook-owned app Instagram being the most popular in the country. Twitter, Facebook and YouTube are all blocked.
Along with Telegram, Instagram was also temporarily banned on Sunday, with Iranian social media users purportedly uploading screen shots of the app not working.
An organizing tool
Official media coverage has provided few details about the week's protests, which represent the largest show of public dissent since the 2009 Green Revolution. And with independent media coverage from inside the country limited at best, social media has played a crucial role for many of the protesters, largely believed to be young people adept at social media.
Many of the young protesters are demonstrating against a maelstrom of sociopolitical woes. They feel disenfranchised by the country's economic downturn, widespread corruption, rising fuel and food prices and dissatisfaction with the rule of Supreme Leader Ayatollah Ali Khamenei.
Since the demonstrations began last Thursday, 21 people have been killed and 450 people have been arrested during the anti-government rallies.
Many of Iran's anti-government protesters have been using apps like Telegram and Instagram to organize. Telegram's public channels have played an essential role in broadcasting information to a wide audience, while the encrypted messaging feature has served as a way to disseminate videos and pictures of the deadly clashes.
Interior Minister Abdolreza Rahmani Fazli said on Sunday that the misuse of social networks by some individuals was "causing violence and fear," and that "such behavior will be smashed," according to IRNA.
But since the ban, many Iranian citizens have been able to continue accessing Telegram and Instagram apps using illegal VPN software.
Mostafa, an Iranian student whose last name has been withheld out of concerns for his safety, told CNN that getting around filtering and censorship was a priority -- and that he was using a Chinese anti-filtering app to circumvent the ban.
"We are being censored," he said. "If I didn't know I was in Iran, I would think I am Nazi Germany."
He added that elderly people have been asking younger internet users how to bypass the censors.
Iranian-American Middle East analyst Holly Dagres said access to VPNs, which are easily bought at shops, aren't necessarily safe from the government's gaze.
"There are times when the Iranian government puts them (VPNs) out on the market to crack down on activists and those vocal against the establishment. Despite this fact, many Iranians still use VPNs because they are not versed in internet security, but very well versed in bypassing censorship," she said.
The government has said it will lift restrictions by Friday in areas that have returned to calm, according to state media.
A history of censorship
It's not the first time Iran has banned an app.
After then-President Mahmoud Ahmadinejad's re-election in 2009, protesters used Twitter to help coordinate and organize the Green Movement, where millions took part after accusations of widespread election fraud.
Iran's leaders responded to the demonstrations, also known as the "Twitter revolution" by blocking access to Twitter and other social media sites. Ahmadinejad has since joined the app.
Iran is not the only country to clamp down on social media in this way.
In 2011, after Tunisia's success in ousting its leader, Egyptians followed suit, using Twitter to organize mass demonstrations that called for an end to President Hosni Mubarak's rule.
But as the demonstrations grew, Mubarak's government pulled the plug on Twitter, cutting off thousands of Egyptian users from accessing the social media site.
During Hong Kong's 2014 Umbrella Revolution, where thousands of people demonstrated for universal suffrage over 79 days, Beijing moved swiftly to quash all reports of dissent from the former British colony.
The Chinese government, which maintains strict controls over the internet and social media, blocked mainland access to Instagram and posts related to the demonstrations on popular Chinese messaging sites like Weibo and Wechat.
But the activists, many of them students, found a technological loophole to stay connected and spread their message using the peer-to-peer "mesh messaging" app FireChat. The app works by creating its own network outside the internet, relying on a Bluetooth or Wi-Fi link that exists between two phones.