Iran has released detained British-Australian academic Kylie Moore-Gilbert in exchange for three Iranians held abroad, according to Iran state TV.

Ms Moore-Gilbert was a Melbourne University lecturer on Middle Eastern studies when she was picked up at Tehran airport while trying to leave the country after attending an academic conference in 2018.

She was sent to Tehran’s Evin prison, convicted of spying and sentenced to 10 years behind bars. Ms Moore-Gilbert had vehemently denied the charges and maintained her innocence.

The state TV report said that the three Iranians released in the swap had been detained for trying to bypass sanctions.

Ms Moore-Gilbert is one of several people held in Iran on internationally criticised espionage charges that their families and rights groups say are unfounded.

Kylie Moore-Gilbert
Kylie Moore-Gilbert has been in Iran since 2018 (Iranian State Television via AP)

It was not immediately clear when Ms Moore-Gilbert would arrive back in Australia.

State TV aired video showing her with a grey hijab sitting at what appeared to be a greeting room at one of Tehran’s airports. She wore a blue face mask under her chin.

The timing of her release remained unclear but the TV footage showed faint sunlight streaming through windows during the swap. Later, footage showed Ms Moore-Gilbert being escorted to a large grey van after nightfall.

The footage showed three men with Iranian flags over their shoulders – those freed in exchange for her being released. State TV earlier described them as “economic activists” without elaborating. Iran’s deputy foreign minister Abbas Araghchi welcomed them at the airport.

International pressure on Iran to secure Ms Moore-Gilbert’s release has escalated in recent months following reports that her health was deteriorating during long stretches of solitary confinement and that she had been transferred to the notorious Qarchak Prison, east of Tehran.

Ms Moore-Gilbert has gone on hunger strikes and pleaded for the Australian government to do more to free her. Those pleas included writing to the prime minister that she had been subjected to “grievous violations” of her rights, including psychological torture and solitary confinement.