GENEVA — The UN rights office said on Tuesday it was alarmed by reports that live ammunition was used against protesters in Iran and had caused a significant number of deaths across the country.

Demonstrations broke out in the Islamic republic on Friday after Tehran announced the price of petrol would be raised by as much as 200 percent in the sanctions-hit country.

The UN human rights office was "especially alarmed that the use of live ammunition has allegedly caused a significant number of deaths across the country," spokesman Rupert Colville told reporters.

Iran has been largely offline since internet restrictions were imposed the day after the demonstrations began.

Colville said casualty details were hard to verify, in part because of the internet shutdown.

But he added: "Iranian media and a number of other sources suggest dozens of people may have been killed and many people injured during protests in at least eight different provinces, with over 1,000 protesters arrested."

"We urge the Iranian authorities and security forces to avoid the use of force to disperse peaceful assemblies."

The full extent of the protests remains unclear, largely as a result of the internet restrictions.

But the demonstrations have seen masked young men set alight petrol stations, banks and other public property.

Colville also called on protesters to demonstrate peacefully, "without resorting to physical violence or destruction of property". — AFP