There are fears for the wellbeing of the 2023 Nobel peace prize winner Narges Mohammadi after she was detained by Iranian security forces at a memorial ceremony for a human rights lawyer in the eastern city of Mashhad.

Mohammadi, 53, who was granted temporary leave from prison on medical grounds in December 2024, was newly detained along with several other activists at the memorial for Khosro Alikordi, who was found dead in his office last week.

Mohammadi’s brother, Mehdi who was present at the ceremony, confirmed her arrest, her foundation said.

A still from footage that shows Narges Mohammadi speaking at the memorial event in Mashhad. Photograph: Instagram

Speaking to the Guardian, a member of Mohammadi’s team who requested anonymity said: “Her arrest earlier today appears directly linked to her public remarks in Mashhad following Khosrow Alikordi’s suspicious death. At his memorial, human rights activists gathered to protest against what they view as a suspicious and potentially state-linked killing.”

Officials in Iran’s Razavi Khorasan province said Alikordi suffered a heart attack, but a tightening security crackdown that coincided with his death has raised questions about its circumstances. More than 80 lawyers have signed a statement demanding more information.

“Alikordi was a prominent figure among Iran’s community of human rights defenders,” the New York-based Center for Human Rights in Iran said on Thursday. “Over the past several years, he had been repeatedly arrested, harassed and threatened by security and judicial forces.”

Mohammadi’s family members said security and police forces used teargas and violence to disperse people who had gathered for Alikordi’s memorial. Speaking from Paris, Mohammadi’s husband, Taghi Rahmani, told the Guardian he was worried not only for his wife but also for the other rights activists arrested at the same time.

Rahmani described the arrest as a part of an escalating strategy by the Iranian authorities to suppress dissent. “This is a targeted attack on democracy and the right to freedom of expression,” he said.

Mohammadi’s children, Ali and Kiana, said they were also worried for their mother and the other activists. “She had a surgery just a year ago and many others arrested have also been fighting medical conditions,” Ali told the Guardian. “She was arrested two hours ago and we still don’t know where my mother is.

“These people don’t belong in the prison.”

Footage from the memorial ceremony showed Mohammadi at a microphone, calling out to the crowd and starting a chant in the name of Majidreza Rahnavard, who was publicly hanged by the Iranian authorities in 2022.

There was no immediate comment from Iran over its detention of Mohammadi and it was not clear whether authorities would return her to prison to serve the rest of her term. Supporters had cautioned for months she was at risk of being put back in jail.

Hasan Hosseini, the city governor of Mashhad, said prosecutors ordered security officials to temporarily detain some participants at the ceremony over the chanting of “norm-breaking” slogans, Iranian state television reported. Hosseini described the detentions as preventive to protect those there from others in the crowd.

Prior to her release last December, Mohammadi had been imprisoned since November 2021 for convictions relating to her campaign against capital punishment and the obligation for women in Iran to wear the hijab.

Her supporters say she suffered multiple heart attacks in prison before undergoing emergency surgery in 2022. Late last year, her lawyer said doctors had found a bone lesion they feared could be cancerous and which was later removed.

“Her health could deteriorate very quickly under these conditions,” Rahmani said. “The repression inside the mosque today was carried out with extreme brutality. Teargas was fired, and Narges and other activists were beaten even though they have serious health issues.”

Mohammadi’s sentence was supposed to be suspended for three weeks when she was released last year, but her time out of prison lengthened, possibly because of pressure from activists and western powers. She remained free even during the 12-day war between Iran and Israel in June.

She kept up her activism with public protests and international media appearances, including demonstrating at one point in front of Evin prison, the notorious facility in Tehran where she was held.

Chirinne Ardakani, Mohammadi’s Paris-based lawyer, said: “I am calling for the immediate release of my client, as well as of all the human rights activists who have been arbitrarily detained alongside her. I also reiterate my client’s demand that truth and justice be established regarding the suspicious circumstances surrounding Alikordi’s death, for which we have reason to believe the state bears responsibility.”

Mohammadi’s family said they do not know in whose custody she is being held, with Ali adding: “My mother could be in the custody of the Revolutionary Guards or the security forces or police. We don’t know anything.”

Rahmani said: “We urge the western media to continue following events in Iran and to please keep reporting.”

Associated Press and Agence France-Presse contributed to this report