Iran vowed Sunday to severely punish "mercenaries" arrested over nationwide street unrest sparked by a fuel price hike, as much of the country came back online after a week-long internet blackout.

Authorities say calm has been restored and they have announced plans to hold a pro-government demonstration to condemn the "rioters" at Tehran's Enghelab Square on Monday afternoon.

The protests broke out on November 15, hours after a surprise announcement that petrol prices were being raised by as much as 200 percent with immediate effect.

A Basij militia commander said the unrest sparked by the fuel price hike amounted to a "world war" against Iran that had been thwarted
A Basij militia commander said the unrest sparked by the fuel price hike amounted to a "world war" against Iran that had been thwarted AFP / ATTA KENARE

Highways were blocked, banks and petrol stations set ablaze and shops looted as the demonstrations turned violent and spread to dozens of urban centres across the country.

Citing law enforcement officials, Fars news agency said on Sunday that 180 ringleaders had been arrested over the street violence, which it has blamed on enemies abroad.

"We will certainly respond in accordance to the viciousness carried out by them," said Rear-Admiral Ali Fadavi, deputy commander in chief of the Islamic Revolutionary Guard Corps.

"We have arrested all stooges and mercenaries who have explicitly made confessions that they have been mercenaries of America, of Monafeghin and others."

Basij militia women attend a Tehran press conference where a Revolutionary Guards commander warned that Iran will severely punish "mercenaries" arrested over a recent wave of street violence
Basij militia women attend a Tehran press conference where a Revolutionary Guards commander warned that Iran will severely punish "mercenaries" arrested over a recent wave of street violence AFP / ATTA KENARE

Monafeghin is a term Iran uses to refer to the People's Mujahedeen of Iran, an exiled opposition group it considers a "terrorist" cult.

The government said the fuel price hike would allow it to provide welfare payments to the needy in Iran, where many have struggled to make ends meet since the US reimposed sanctions after withdrawing from a landmark nuclear deal.

Rear-Admiral Ali Fadavi, deputy commander in chief of the Revolutionary Guards, said about protest leaders that "we have arrested all of them and, God willing, the judiciary will give them maximum punishments"
Rear-Admiral Ali Fadavi, deputy commander in chief of the Revolutionary Guards, said about protest leaders that "we have arrested all of them and, God willing, the judiciary will give them maximum punishments" AFP / ATTA KENARE

Fadavi said "we have arrested all" protest leaders.

"God willing, the judiciary will give them maximum punishments", he added.

The Guards commander was speaking at a gathering of female members of the Basij, a militia loyal to Iran's establishment.

Iranians struggled to adjust to life offline after a week long and near total internet blackout
Iranians struggled to adjust to life offline after a week long and near total internet blackout AFP / ATTA KENARE

On Friday, a Basij commander said the unrest triggered by the fuel price hike amounted to a "world war" against Iran that had been thwarted.

Brigadier General Salar Abnoosh said interrogations had revealed a "coalition of evil" of Israel, the United States and Saudi Arabia was behind the "sedition", according to ISNA news agency.

Officials have confirmed five deaths in the unrest, while Amnesty International said more than 100 demonstrators were believed to have been killed and that the real toll could be as high as 200.

The total number of people arrested over the unrest remains unclear, but the UN human rights office put it at more than 1,000 on Tuesday.

At the height of the unrest, a near-total internet blackout was imposed in a step seen as aimed at curbing the spread of videos of the violence.

The outage had helped to "disrupt the complicated" plans by Iran's enemies, Abnoosh said on Friday.

Connectivity was back on Sunday for much of the country except for its mobile telephone networks, said NetBlocks, a website that monitors global internet disruptions.

"In the 186th hour of #Iran's national internet shutdown, mobile connectivity remains scarce while fixed-line/wifi is still shut in several regions," it tweeted at 2:13 pm (1043 GMT).

NetBlocks later said internet connectivity on Irancell was back up at 98 percent, although two other key mobile service providers -- MCI and RighTel -- were down at zero and one percent respectively.

Iran's arch-enemy the United States on Friday slapped sanctions on the Islamic republic's telecommunications minister over the outage.

It issued a call Saturday for Facebook, Instagram and Twitter to suspend the accounts of Iranian government officials until coverage is re-established across the country.

Since May last year -- when the US unilaterally pulled out of the multilateral 2015 nuclear deal, ahead of reimposing biting sanctions -- the Iranian rial has plummeted and inflation has soared.

The International Monetary Fund expects the country's economy to contract by 9.5 percent this year.