Australia does not believe that the detentions of two British-Australian women and one Australian man in Iran are politically motivated, according to country foreign minister Marise Payne.

Jolie King and her Australian friend Mark Firkin have been detained in the infamous Evin prison in Tehran for about 10 weeks after being reportedly arrested for flying a license-free drone.

In another case, a second British-Australian woman, a Melbourne-based scientist whose name was not published, has been in the same prison for nearly a year

While the news of the trio's arrests just arrived this week, Senator Payne said she had "often" raised her cases with her Iranian counterpart Javad Zarif.

And Senator Payne denied that the arrests were politically motivated, although some speculated that the trio were being held in hopes of politically pressurizing Iran in a series of ongoing disputes with Western countries.

"We have no reason to believe that these arrests are linked to international concerns about the Iranian nuclear program, UN sanctions or maritime safety in terms of civilian security," Senator Payne told All Three Prisoners were treated well.

"The government has made efforts to ensure that they are treated fairly, humane and in accordance with international standards."

The news of the three prisoners this week has worsened in relations between Britain and Iran. Triggers included the seizure of an Iranian oil tanker, Adrian Darya 1, by the Royal Marines near Gibraltar in July.

Iran responded by seizing British flagged oil tanker Stena Impero in another chapter of a campaign to disrupt shipping in the Strait of Hormuz.

While Britain released the Adrian Darya 1, the Stena Impero is still held by Iran.

Relations between Tehran and the West, particularly the United States, have also been strained by attempts to curtail Iran's nuclear program.

Ms. King and Mr. Firkin, who left home in Perth, Western Australia, in 2017, posted information about their trip to Asia prior to their arrest on social media for allegedly attempting to take aerial photos with a drone.

Pouria Zeraati, editor-in-chief of Iranian television channel Manoto TV, said on Twitter that the couple had not yet been to court.

"The family says it was a misunderstanding, and Jolie King and her fiancé Mark Firkin did not know about Iranian law, which prohibits unmanned drone flights," Zeraati tweeted.

The couple's relatives have pleaded for their immediate release in a statement by the Australian Department of Foreign Affairs and Commerce.

"Our families hope to bring Mark and Jolie home safely as soon as possible," the statement said.

Evin Prison, the main detention center for political prisoners in Iran, also houses 41-year-old Ms. Zaghari-Ratcliffe, a British-Iranian mother of a person whose espionage charge has been running since 2016.

While Iran has not publicly commented on any of the arrests, its Foreign Minister Mohammad Javad Zarif proposed in April to exchange Ms. Zaghari-Ratcliffe for Negar Ghodskani, an Iranian woman in prison in the US.