This year's winner of the Nobel Peace Prize has condemned the arrest in Iran of Iranian Peace laureate Narges Mohammadi, dubbing it a "confession of fear" by the Islamist regime.

"The Islamic Republic understands what dictatorships always understand: a fearless voice, once heard, cannot be unheard. That is why they strike in public. That is why they choose brutality. They want to teach an entire society that even grief is forbidden when it becomes solidarity," Venezuela's María Corina Machado posted on X on Saturday.

The Norwegian Nobel Committee sharply criticized the arrest the previous day. The 2023 laureate was detained by security forces on Friday during a memorial event in the eastern Iranian metropolis of Mashhad, according to supporters.

The committee "is deeply concerned by today’s brutal arrest of Narges Mohammadi alongside a number of other activists," it said in a statement posted on its website on Friday.

It urged the Iranian authorities to immediately disclose where Mohammadi is, ensure her safety and well-being, and release her unconditionally.

"Given the close collaboration between the regimes in Iran and Venezuela, the Norwegian Nobel Committee notes that Ms Mohammadi is arrested just as the Nobel Peace Prize has been awarded to the Venezuelan opposition leader, Maria Corina Machado."

Iranian officials said Mohammadi and at least seven other activists were detained on Friday to protect them from possible violence, a claim that activists have rejected.

Local media on Saturday cited the Mashhad governor's office in north-eastern Iran as saying that the detentions followed a protest led by Mohammadi, during which harsh slogans against Iran's political leadership were reportedly shouted.

The office claimed the activists needed protection because there were also Islamic hardliners at the event. Due to the activists' slogans, there were fears of violent clashes between the two groups, the governor's office said.

Activists and opposition sources have dismissed this claim, saying the security guards themselves used insults and excessive force during the raid on the ceremony and the detentions.

They also said at least 40 activists were detained, including on charges of supporting the return to a monarchy in the country.

The detentions were made during a memorial ceremony for the late lawyer Khosrow Alikordi at a mosque in Mashhad. According to official reports, 46-year-old Alikordi died of a heart attack several days ago. Opposition sources say he died from torture while in custody.

Alikordi, a human rights lawyer who represented political prisoners, was widely respected among activists, and his death shocked Iran's human rights community. He was known for his critical approach toward the judiciary, which landed him on the Islamic system's political blacklist.

Mohammadi was awarded the Nobel Peace Prize two years ago for her fight against the oppression of women in Iran, her opposition to the death penalty and her advocacy for human rights and freedom.

She had been serving a lengthy prison sentence in Tehran's notorious Evin prison before being released around a year ago due to health problems.