The US Treasury Department on Friday issued guidance expanding the range of internet services available to Iranians despite US sanctions on the country, amid protests around Iran following the death of a 22-year-old woman in custody.

Officials said the move would help Iranians access tools that can be used to circumvent state surveillance and censorship, but would not entirely prevent Tehran from using communications tools to stifle dissent, as it did by cutting off internet access for most citizens on Wednesday.

“As courageous Iranians take to the streets to protest the death of Mahsa Amini, the United States is redoubling its support for the free flow of information to the Iranian people,” Deputy Treasury Secretary Wally Adeyemo said.

"With these changes, we are helping the Iranian people be better equipped to counter the government’s efforts to surveil and censor them."

Adeyemo added that Washington in coming weeks would continue to issue guidance.

Public outrage in Iran over Mahsa Amini's death last week showed no sign of abating after days of protests in Tehran and other cities, with protesters torching police stations and vehicles earlier on Thursday and reports of security forces coming under attack.

Amini, a Kurdish woman, was arrested by the morality police in Tehran for wearing "unsuitable attire" and fell into a coma while in detention. The authorities have said they would investigate the cause of her death.

Internet monitoring group Netblocks on Thursday said a new mobile internet disruption has been registered in Iran, where access to social media and some content is tightly restricted. NetBlocks reported "near-total" disruption to internet connectivity in the capital of the Kurdish region on Monday, linking it to the protests.

Washington has long provided some internet-related exceptions to its sanctions on Iran, but Friday's update to the general license seeks to modernise them, the Treasury said.

The new license includes social media platforms and video conferencing and expands access to cloud-based services used to deliver virtual private networks (VPNs), which provide users with anonymity online, and other anti-surveillance tools, according to a Treasury official, who briefed reporters on the license on condition of anonymity. (Reuters)