Iran has promised to severely punish "mercenaries" arrested over nationwide street protests sparked by a fuel-price rise as much of the country came back online after a week-long internet blackout.

A senior commander of Iran's elite Islamic Revolutionary Guard Corps (IRGC) on Sunday urged the country's judiciary to mete out harsh sentences to those involved in the deadly demonstrations.

"We caught all the mercenaries who openly confessed they were doing mercenary work for America and, God willing, the judicial system of the country will give them maximum punishments," Rear Admiral Ali Fadavi, a deputy commander of IRGC, was quoted as saying by the Mizan news site.

Citing law enforcement officials, Fars news agency said on Sunday that 180 ringleaders were arrested over the street violence.

Iran's leadership has blamed "thugs" linked to exiles and foreign foes - the United States, Israel, and Saudi Arabia - for stirring up unrest, which led to some of the worst violence in the country in a decade.

"There are no non-Muslim countries around us, but unfortunately they carried out these evil acts in violation of both Islam and neighbourliness," said Fadavi. "We will definitely give a response appropriate to the vicious acts they did."

Painful price rises

An increase in fuel prices sparked demonstrations across the country on November 15. Banks, shops and petrol stations were set on fire, while security forces responded with violence.

Amnesty International said at least 106 protesters were killed. Iran disputes that figure without offering its own.

Fadavi said several people were killed during the protests after being shot with handguns at close range, which he said indicated the shooters were among the crowds.

Amnesty said security forces shot into crowds from rooftops and, in one case, from a helicopter.

Iranian authorities have said about 1,000 demonstrators were arrested.

The Center for Human Rights in Iran, a New York-based advocacy group, said on its website that a tally based on official figures and credible reports suggested "a minimum of 2,755 people have been arrested with the actual minimum number likely being closer to 4,000".

Demonstrations started in several towns after the government announced gasoline price hikes of at least 50 percent. They spread to 100 cities and towns and quickly turned political with protesters demanding top officials step down.

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

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

Internet returns

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.

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.

NetBlocks 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.

The US on Friday slapped sanctions on the Islamic Republic's telecommunications minister over the outage.

Washington issued a call on 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 nuclear deal with world powers, 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.

SOURCE: ALJAZEERA