The blackout, which Iran has started rolling back, made it difficult for protesters to communicate.

The United States has imposed sanctions on Iran‘s communications minister for his role in “widescale internet censorship”, a reference to a five-day-long nationwide shutdown meant to help stifle protests against fuel price hikes by Tehran.

The sanctions imposed Friday on Mohammad Javad Azari-Jahromi would block, or “freeze”, any of his property under US jurisdiction, the Department of the Treasury said in a statement, adding that US regulations generally prohibit dealings by Americans, or those transiting the US, in such property.

The internet blockage, which Iran said on Thursday it had begun to roll back, made it difficult for protesters to post videos on social media to generate support and also to obtain reliable reports on the extent of the unrest. Amnesty International has said more than 100 people were killed in demonstrations.

“Iran’s leaders know that a free and open internet exposes their illegitimacy, so they seek to censor internet access to quell anti-regime protests,” Treasury Secretary Steven Mnuchin said in a statement.

“We are sanctioning Iran’s Minister of Information and Communications Technology for restricting internet access, including to popular messaging applications that help tens of millions of Iranians stay connected to each other and the outside world,” he added.

‘Identified and arrested’

On Friday, Iran’s Revolutionary Guard (IRGC) arrested about 100 leaders of the protests that erupted last week, said Gholamhossein Esmaili, spokesman for Iran’s judiciary, according to the official IRNA news agency.

“Approximately 100 leaders, heads and main figures of the recent unrest were identified and arrested in various parts of the country by the Islamic Revolutionary Guards Corps,” Esmaili said.

A large number of people arrested who had taken part in the protests but did not take part in causing damage or setting fires have been released, judiciary spokesman Esmaili said, according to Mizan – the news site of the judiciary.

Iranian authorities say about 1,000 total demonstrators have been arrested. Anyone who created insecurity or damaged public property will face “severe punishment”, the head the judiciary, Ebrahimi Raisi, said.

Meanwhile, the IRGC said calm had returned across Iran on Thursday, state TV reported, also showing thousands marching in pro-government rallies in about half a dozen cities on Friday.

‘Repressive internet censorship’

Azari-Jahromi has advanced Tehran’s policy of “repressive internet censorship” while in office, according to the Treasury Department, which described him as a former intelligence official who has been involved in surveillance against opposition activists.

On Thursday, Iranian media said the country’s National Security Council, which had ordered the shutdown, approved reactivating the internet gradually in some areas.

Azari-Jahromi has pointed out in local media interviews that the shutdown was implemented by the council, but has said it was important for security reasons.

The youngest minister in Iranian President Hassan Rouhani‘s cabinet, Azari-Jahromi reportedly has presidential ambitions, according to Iran analysts.

“We will hold members of the Iranian regime accountable for their violent repression of the Iranian people,” US Secretary of State Mike Pompeo wrote in a tweet.

In response to demonstrators who demanded that top officials step down, Tehran has blamed “thugs” linked to exiles and foreign foes – the US, Israel and Saudi Arabia – for stoking the unrest.

The protests in Iran come as the economy has been crippled by sanctions reimposed since US President Donald Trump withdrew from Tehran’s 2015 nuclear deal with major powers.