The families of a British-Australian woman and her Australian partner have pleaded for their immediate release from a notorious Iranian prison.

Vloggers Jolie King and Mark Firkin, who live in Perth, Western Australia, have been held for the past 10 weeks in Tehran’s Evin prison, with Ms King recently completing a lengthy period in a tiny one-person cell.

Ms King had been “scared”, “disoriented” and “intimidated” while kept in solitary confinement, the partner of British-Iranian Nazanin Zaghari-Ratcliffe who is being held captive in the same jail said.

The couple was arrested for flying a drone near the capital Tehran without a licence, Pouria Zeraati, editor in chief at Iranian television station Manoto TV, said on Twitter.

Mr Zeraati, citing unidentified sources, said the couple had not yet stood trial.

“The family says this was a misunderstanding and Jolie King & her fiance Mark Firkin were unaware of the Iranian law which bans drone flights without a licence,” Mr Zeraati tweeted.

He also tweeted photos from their Instagram account and said they had "used drones" before.

Earlier reports said the couple were arrested while camping near a military area around Jajrood in Tehran province.

Another British-Australian woman, an academic from Melbourne who studied at Cambridge, has also been revealed to have been jailed in Evin prison.

The woman is reportedly also being held in solitary confinement.

While the charges against her have not been made public, Iran routinely hands out 10-year-sentences for spying convictions.

Australia's Foreign Minister Marise Payne said she had raised the arrests of the two British-Australian women and the Australian man "many times" with her Iranian counterpart Mohammad Javad Zarif.

Ms Payne said she not believe the arrests of Perth couple Mr Firkin and Ms King, or the earlier arrest of the Melbourne woman are "related to broader issues".

Analysts believe that Iranian security agencies often use prisoners as bargaining chips in negotiations with the West.

Nazanin Zaghari-Ratcliffe, a British-Iranian woman who has been jailed in Iran Credit: Family handout/PA

Evin prison, the main detention centre for Iran’s political prisoners, also houses 41-year-old Mrs Zaghari-Ratcliffe, a British-Iranian mother of one who is midway through a five year sentence on spying charges which began in 2016.

Mrs Zaghari-Ratcliffe’s husband, Richard Ratcliffe, said on Thursday Ms King was now in the same part of the jail as his wife, having come through a torrid time in solitary confinement.

“I know that the girl who is in now with Nazanin came through scared and disoriented and obviously had been quite intimidated by being interrogated for all that time in solitary,” Mr Ratcliffe told Australian media.

Mr Ratcliffe said his wife had spent more than eight months in solitary confinement and had described Evin prison’s solitary cells as being “about the size of a double bed” and with no windows or natural light, meaning “it was a lightbulb on the whole time”.

It is not known whether Mr King is also in solitary confinement.

News of the three prisoners this week comes amid a downturn in relations between Britain and Iran, sparked by issues including the seizure by the Royal Marines in July of an Iranian oil tanker near Gibraltar.

Britain’s Foreign and Commonwealth Office says Australia’s DFAT is handling all three cases.

Ms King, travelling on her Australian passport, and Mr Firkin, had been posting about their travels during their lengthy trip, which began in 2017, on their The Way Overland accounts on YouTube and Instagram.

After driving from Perth to Darwin and island-hopping to Asia, they had driven west through countries including India, Pakistan and China before arriving in Iran.

They had ultimately planned to finish in the UK.

“Our biggest motivation behind the vlogs is to hopefully inspire anyone wanting to travel, and also try to break the stigma around travelling to countries which get a bad rap in the media,” the couple wrote in one early post.

DFAT has been negotiating with Iranian authorities for the release of all three Australian passport-holding detainees for several weeks.

While Iran has not commented publicly on any of the arrests, in April its foreign minister Mohammad Javad Zarif proposed swapping Mrs Zaghari-Ratcliffe for Negar Ghodskani, an Iranian woman in jail in the US.

Dominic Raab will discuss the case with his Iranian counterparts Credit: Kirsty O’Connor/PA

British Prime Minister Boris Johnson and Foreign Secretary Dominic Raab are reportedly preparing to confront Iranian counterparts on their detention of Britons in Iran at a UN meeting in New York later this month.

The Times reported Mr Raab had written in a letter to MPs with constituents detained in Iran, saying: “We will not accept Iran using our citizens a diplomatic leverage.”

Defence Secretary Ben Wallace, speaking on Wednesday, called on Iran to “follow the international rule of law” and to “release people that are being detained in the way they have been over the last few years”.

Mr Ratcliffe also called on Britain and Australia to increase pressure on Iran to ensure that in its prisons that “no-one’s being tortured, that people are getting health rights, that no-one’s ill, and that no-one’s being kept in solitary confinement”.