Mark Firkin and Jolie King, who were arrested in July, have been freed following "very sensitive negotiations" with Tehran, Foreign Minister Marise Payne said in Canberra early on October 5.

She added that they were on their way home and in "good health and in good spirits."

Payne said a third Australian citizen who was arrested a year ago by Iranian authorities and "convicted," Melbourne University Academic Kylie Moore-Gilbert, remains in detention.

In September, Iran's semiofficial Fars news agency quoted a judiciary spokesman who said Moore-Gilbert also had been detained on charges of spying.

Payne said Moore-Gilbert's case was complex.

"We are continuing our discussions with the Iranian government," she said. "We don't accept the charges upon which she was convicted and we will seek to have her returned to Australia."

Meanwhile, Iranian state TV reported that an Iranian student detained in Australia for 13 months on charges of trying to circumvent U.S. sanctions on military equipment has returned to Tehran after being released.

Reza Dehbashi, a postgraduate student at the University of Queensland in Brisbane, was arrested in 2018 for allegedly "attempting to purchase and transfer advanced American military radar equipment via Dubai to Iran."

The Iranian state TV report said Australia's legal system "intended to extradite Mr. Dehbashi to America, but he was eventually released" after Iran's Foreign Ministry "resolved" the issue.

The broadcaster early on October 5 showed footage of Dehbashi arriving at Tehran's Imam Khomeini International Airport and hugging a tearful woman apparently from his family.

It said Dehbashi had been working on a "skin-cancer detection device" at the time of his arrest and that he had dismissed the charges as "a misunderstanding" and "unfair."

News of his return came hours after Canberra said the Australian travel-blogging couple had been reunited with their family in Australia following "very sensitive negotiations" with Iran.

Firkin and fiancee King were arrested in July and were alleged to have used a drone to take pictures of military sites, judiciary spokesman Gholamhossein Esmaili was quoted by the judiciary-affiliated Mizan news agency as saying last month.

Media reports suggested they were being held in Tehran's Evin prison.

The couple had been documenting their journey on social media for the past two years but went silent in July.

Tehran on September 17 acknowledged for the first time that it was holding two British-Australian citizens and an Australian national for allegedly spying. King is a dual British-Australian citizen.

The arrests came at a time of increased tensions between Iran and Western countries over a number of issues, including Iran's decision to reduce its nuclear commitments under the 2015 nuclear deal.

In recent years, several foreigners and dual nationals have been jailed in Iran on espionage charges.

Iranian authorities have not provided any solid evidence to back their claims.

With reporting by AFP, dpa, and AP