"If you're in Iran, you should leave as soon as possible," an updated government travel advisory said.

"There's ongoing violent nationwide protests that may further escalate without notice... the security situation is volatile," it added.

The protest wave began on December 28 with a shutdown by merchants in Tehran, triggered by anger over the rising cost of living. They have since spread to other areas, especially the west, which is home to Kurdish and Lor minority groups.

Security forces have now killed at least 27 protesters, including five minors under the age of 18, the Norway-based NGO Iran Human Rights (IHR) said. Iranian authorities say members of security forces have also been killed, including a policeman who was shot dead on Tuesday.

Australia's embassy in Tehran suspended operations last year during conflict between Iran and Israel, and this week's statement said its "ability to provide consular assistance in Iran is extremely limited".

"Australians, including dual nationals, are at a high risk of being detained," it added.

The demonstrations are the most serious protest movement in Islamic republic since the 2022-2023 nationwide rallies sparked by the death in custody of Mahsa Amini, who had been arrested for allegedly violating the strict dress code for women.