Australians have been advised to leave Iran now, as ongoing protests may make it "impossible to leave later".
Updated advice from Smartraveller warned that though flights are still departing the West Asian nation, that could soon change.
"Commercial options to depart are still available but becoming more limited," it read.
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"Airspace closures and flight cancellations could happen soon, making it impossible to leave later."
Airspace closures and flight cancellations could occur at short notice if the already volatile security situation in Iran continues to deteriorate.
The internet is already down and phone lines have been cut off amid nationwide protests.
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The US-based Human Rights Activists News Agency says 538 people have been killed and 10,600 detained.
According to Iran Human Rights (IHRNGO), an independent, Norway-based non-profit that monitors the human rights situation in the country, the death toll may be as high as 2000.
"Security forces' response to protests has been severe, and many protesters and bystanders have been injured, killed or detained," Smartraveller said in updated advice.
"Avoid public gatherings and protests. Australians, including dual nationals, are at a high risk of being detained."
It urged all Australians in Iran to leave immediately.
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The Australian Embassy's operations have been suspended and the Australian government's ability to provide consular assistance in Iran is extremely limited.
Australians who choose to remain against government advice will be responsible for their own safety.
They should be prepared to shelter in place for an extended period and stock up on food, water and medication.
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