Iranian human rights campaigner Narges Mohammadi has been transferred from jail to a Tehran hospital amid concern over her deteriorating health.

Iranian authorities granted Mohammadi "a sentence suspension on heavy bail", a foundation run by her family said on Sunday.

Last week Mohammadi's family and supporters warned she could die in prison after suffering two suspected heart attacks earlier this year.

Mohammadi, 54, was awarded the 2023 Nobel Peace Prize for her activism against female oppression in Iran and promoting human rights.

After pleas from her family for her to be transferred from prison, Mohammadi is "now at Tehran Pars Hospital to be treated by her own medical team", ​the Narges Mohammadi Foundation said in a statement.

She had spent 10 days hospitalised in Zanjan in northern Iran, where she had been serving her sentence.

Mohammadi's Paris-based husband said "she is not in a favourable general condition" and that "her status remains unstable", in a statement over the weekend.

The activist is believed to have lost about 20kg (three stone) while in prison, and has difficulty speaking and is barely recognisable, according to her lawyer Chirinne Ardakani.

In 2021, Mohammadi began serving a 13-year sentence on charges of committing "propaganda activity against the state" and "collusion against state security", which she denied.

In December 2024, she was given a temporary release from Tehran's notorious Evin prison on medical grounds.

Mohammadi was arrested last December for making "provocative remarks" at a memorial ceremony, Iranian authorities said at the time. Her family said she was taken to hospital after being beaten during the arrest.

In early February, Mohammadi was sentenced by a Revolutionary Court to an additional seven-and-a-half years in prison after being convicted of "gathering and collusion" and "propaganda activities", her lawyer said.

Last month, Mohammadi's brother Hamidreza said his sister had been found unconscious by fellow inmates at Zanjan prison after suffering a suspected heart attack.

The foundation's statement on Sunday said "a suspension is not enough" and that the human rights activist requires "permanent, specialised care".

"We must ensure she never returns to prison to face the 18 years remaining on her sentence," it read.

"Now is the time to demand her unconditional freedom and the dismissal of all charges. No human and women's rights activists should ever be imprisoned for their peaceful work," it said.