Zahra Sedighi-Hamadan had been based in Iraqi Kurdistan but was arrested by the Iranian Revolutionary Guards on October 27 while seeking to flee to neighbouring Turkey, Amnesty said.

After a 53-day period of "forced disappearance" in solitary confinement in the northwestern Iranian city of Orumiyeh, she was in January brought before Iranian prosecutors and charged with "spreading corruption on earth" and "promoting homosexuality".

Amnesty said that the charges stemmed from her public defence of LGBTI rights on her social media platforms and an appearance in a BBC documentary aired in May 2021 about the abuses that LGBTI people suffer in the Kurdistan Region of northern Iraq (KRG).

She had decided to leave Iraqi Kurdistan after being detained by the regional authorities there. It appears she crossed into Iran again before seeking to head for Turkey.

"Iran's authorities must immediately release.... Zahra Sedighi-Hamadani, unjustly detained since October 2021 due to her real or perceived sexual orientation and gender identity and her public defence of LGBTI rights," Amnesty said.

Activists frequently decry Iran's treatment of LGBTI individuals.

Homosexuality is banned in Iran with its penal code explicitly criminalising same-sex sexual behaviour for both men and women.

Iranian gay rights group 6Rang (6 Colours) had initially drawn attention to the disappearance of Sedighi-Hamadani -- also known as Sareh -- in December.

It said before leaving the KRG she had sent the group videos to be made public in case she failed to make it to safety.

"We, the LGBTI community, are suffering. Whether through death or freedom, we will remain true to ourselves," she said in one of the videos.

"I hope to achieve freedom," she added, also alleging she had been tortured with methods including electrocution while in Iraqi Kurdish custody.