The lawyer representing Iranian scientist Reza Dehbashi Kivi believes his client's case could be connected to two Australians being released from Iranian custody.

Key points: Australians Jolie King and Mark Firkin were released from Iran after three months in detention

Australians Jolie King and Mark Firkin were released from Iran after three months in detention At the same time, Australia returned Iranian scientist Reza Dehbashi Kivi after 13 months' detention

At the same time, Australia returned Iranian scientist Reza Dehbashi Kivi after 13 months' detention His return to Tehran came despite US requests for him to be extradited there to face charges

Mr Dehbashi Kivi, a 38-year-old University of Queensland research student, has been allowed to return home to Iran after being detained in Australia for more than a year.

News of his release came on the same day two Australian travel bloggers returned home after being jailed in Iran for more than three months.

The timing prompted speculation a prisoner swap had occurred, and Mr Dehbashi Kivi's lawyer, Pouyan Afshar, said he believed it was possible.

"My view is there is some connection between the two events. I cannot say whether one was connected to the other directly, but there has obviously been discussions between the two countries," he said.

Foreign Minister Marise Payne on Saturday announced Iranian authorities had agreed to drop all charges against Perth couple Jolie King and Mark Firkin following long negotiations between Australian and Iranian consular officials.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 7 seconds 1 m 7 s Jolie King and Mark Firkin posted about their travels through Pakistan in June, before they were detained in Iran.

Melbourne University academic Dr Kylie Moore-Gilbert remains behind bars in Iran after being convicted and sentenced to prison.

Mr Dehbashi Kivi returned to Iran on Sunday after Attorney-General Christian Porter opted against extraditing him to the United States.

He had been in custody for 13 months in Australia. US authorities have accused him of conspiring to export American-made electronic military devices to Iran more than a decade ago.

Mr Porter said he decided against extradition because of the specifics of Mr Dehbashi Kivi's case.

"First, this is not the first extradition matter in which a person has not ultimately been surrendered by Australia to the country seeking their extradition," he said in a statement.

"Second, as a matter of longstanding policy, the Australian Government does not comment on the details behind its consideration of particular cases.

"And while it is likely that because of Mr Dehbashi Kivi's nationality some will speculate regarding this matter, consistent with prior practice I do not intend to comment further on the particular details of this case, particularly when any such response from me may diminish our Government's capacity to deal with future matters of this type in Australia's best interests."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 46 seconds 46 s Iranian scientist released from Australian custody

Opposition Leader Anthony Albanese refused to be drawn on the link between the Australian bloggers and Mr Dehbashi Kivi.

"I do note that there is still an Australian who is detained in Iran," Mr Albanese said.

"It's important that commentary bear that in mind and I certainly won't be saying anything that runs the risk of endangering the potential of securing her release and her being brought back to Australia, which would be a very good thing along with the two Australians who are now back here."