DUBAI, United Arab Emirates (AP) — Imprisoned Nobel Peace Prize winner Narges Muhammadi He underwent complex surgery in Iran to remove part of the bone in his right leg due to cancer fears, but was immediately sent back to prison, increasing the risks to his life, rights groups warned.

A letter signed by more than 40 activist groups and sent to the United Nations Human Rights Council called for Muhammadi’s immediate release on medical leave from prison on charges that have long been criticized internationally. It is part of a broader pressure campaign against Iran over Mohammedi’s arrest since the Nobel committee honored him last year.

Meanwhile, another activist set himself on fire in prison last weekend to protest his imprisonment, a group said, at a time when Iran continues to face domestic opposition after years of protests against its theocracy.

“We call on Iranian authorities to stop criminalizing human rights and refrain from calling on human rights defenders, journalists and writers to serve prison sentences while their health conditions are unstable,” the letter dated Monday said.

Iran’s mission to the United Nations did not immediately respond to a request for comment on Tuesday. Iranian state media, which had largely ignored previous campaigns for Mohammedi’s release, did not immediately report on the letter.

Mohammedi, 52, is serving a total prison sentence of 13 years and nine months on charges of collusion against state security and propaganda against the Iranian government. His continued his activism Despite numerous arrests by Iranian authorities and years behind bars. This includes supporting women-led protests across the country. 2022 death of Mahsa Amini.

The letter states that he suffered multiple heart attacks while in detention before undergoing emergency surgery in 2022. In November this year, his lawyer announced that doctors had found a bone lesion they feared might be cancerous, triggering the surgery he underwent on Thursday.

“Despite his doctor’s advice and another request from his legal team that he be given medical leave and a suspended sentence, he was transferred back to prison just two days later,” the letter said.

“Years of imprisonment and months of solitary confinement seriously endangered Mohammadi’s health and exposed him to multiple serious conditions that could not be resolved with a brief and incomplete hospital visit.”

Iran’s economy has been in ruins for years Because of the sanctions imposed by the West. Its people are angry about the devaluation of their currency and corruption in the government. This sparked protests Government pressure on opposition in the country. President-elect Donald Trump’s return to the White House this January has raised some concerns He said he could continue his “maximum pressure” campaign against the Islamic Republic.

Concerns are also growing for other activists detained in Iran. Iran’s New York-based Center for Human Rights said on Saturday that Saeid Gharibi set himself on fire to protest his 15-year sentence and conditions at Adelabad Prison in Shiraz. The center quoted his lawyer as saying that Garibi suffered serious burns on his back and hands and was denied medical care. Iran did not accept the incident.

Last week, a former journalist working for the Voice of America’s Persian service jumped to his death from a building in Tehran to protest the country’s religious leader and the ongoing crackdown on dissidents.