In the aftermath of a woman's death in the custody of the country's morality police, Tehran moved to cut off the internet in what the US Treasury said was a bid "to prevent the world from watching its violent crackdown on peaceful protestors."

The new measure will allow technology companies to "expand the range of internet services available to Iranians," Deputy Treasury Secretary Wally Adeyemo said in a statement.

"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," he said.

Iran has been rocked by a week of bloody protests over the death last week of Amini, who was arrested for "improperly" wearing the Islamic headscarf.

The 22-year-old Kurdish woman spent three days in a coma after being detained by the morality police.

The US Treasury said it was taking action to allow access to software, including anti-virus and malware tools, as well as video conferencing services to support "access to fact-based information to the Iranian people."

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

Billionaire Elon Musk said recently he would ask the Treasury to allow an export license to authorize his Starlink satellite internet firm to provide services to Iran, but Friday's move focuses on software rather than hardware.