Consular assistance is being provided to their families.

"Due to our privacy obligations, we will not comment further," a spokesman for the Department of Foreign Affairs and Trade told AAP on Wednesday.

The charges against the Australian man and two Australian-British women remain unclear.

"All Australian citizens and holders of dual nationality with Australia who are travelling to or through Iran are urged to follow the travel advice on the DFAT Smart Traveller website," the department said.

One of the women, a blogger who was travelling through Asia, and her boyfriend were arrested about 10 weeks ago, The Times of London reported.

The couple had been documenting their travels on YouTube and Instagram, but concerns were raised when they failed to add any new posts for several weeks.

The other woman, an academic who had been lecturing at an Australian university, has been given a 10-year sentence.

While the charges against her also remain unclear, 10-year terms are routinely given in Iran for spying charges, the Times reported.

The three are incarcerated in the Evin jail in Tehran.

The notorious prison is where Iran holds its political prisoners and has a reputation for being the scene of various human rights abuses, including summary executions.

The department's travel advice is currently set to "reconsider your need to travel".

The highest warning level - "do not travel" - applies in some parts of the country.

There is a risk that foreigners, including Australians, could be arbitrarily detained or arrested.

The advice states Australians may be at greater risk if they have a profile that can be seen adversely by Iran, or undertake activities which could attract the attention of its authorities.

Australian Associated Press