Fears are rising for a number of Iranian athletes facing execution after the mountain climber Ali-Sina Mostafavi was put to death by the authorities, the latest in a series of such cases.

Mostafavi, who recorded his climbs of some of the world's highest mountains, including Mount Everest, was executed on 14 October. He had been arrested in April, a few months after anti-government protests. His death came after that of Siavash Jamshidi Kheirabadi, a taekwondo athlete, at the beginning of October, and that of the mixed martial arts fighter Gholamreza Khani Shakarab, who was hanged in May.

Human Rights for Sport, an Oslo-based group of former Iranian athletes that has been documenting these cases, says at least six more people face execution after Iran's supreme court upheld their sentences. They include the swimmer Ali Pishevarzadeh and the footballer Ehsan Hosseinpour, both arrested during the January protests. Also on the list is the boxer Mohammad Javad Vafaei Sani, who was arrested in 2020 over protests a year earlier and whose request for a retrial was rejected last year. The MMA fighter Benyamin Naghdi, the equestrian athlete Taraneh Rahimi and the climber Maryam Siri have also been sentenced to death this year. The group says six athletes have already been executed in cases tied to the January protests or to earlier political charges.

Dr Zohreh Abdollahkhani of the group said: "The Iranian sporting community is under enormous pressure." She said attention raised through other organisations had halted one execution, but only temporarily, and that she is very concerned about all of those sentenced.

The group believes athletes are targeted to send a message to the wider public, noting that the deaths of prominent sportspeople are often widely covered by state-run media. It points to the wrestler Navid Afkari Sangari, executed in September 2020. "He was a role model and very famous in the whole community. What happened to him was also a warning to the whole population," Abdollahkhani said.

Mostafavi's death sentence was upheld by the supreme court at the end of September. He is believed to have suffered physical violence during detention in Kerman before being moved to solitary confinement. He was accused of being an "armed agent of the American-Zionist enemy" and of opening fire on civilians in Azadi Square in Kerman on 24 March, as well as taking part in the January protests. His family are thought to have been summoned to the prison hours before the execution.

Abdollahkhani said reaching those on death row is difficult because relatives are also being targeted by security services. In one case, she said, a sister and brother-in-law have been arrested and the family's phone lines are under surveillance, making direct contact impossible.

The group says 217 Iranian athletes were killed by direct gunfire in January and more than 100 others were detained. Four members of the European parliament wrote to Fifa before the World Cup about athletes facing execution, but Abdollahkhani said they received no reply. A Fifa spokesperson said the body is aware of the concerns and thanked stakeholders for their continued work to raise awareness.

Abdollahkhani also criticised the International Olympic Committee, saying staffing changes had made it hard to raise cases through its human rights and safeguarding structures. The IOC disputed this, saying it has "fully functioning human rights and safeguarding teams". It said it is deeply concerned about affected athletes but, as a non-governmental organisation, lacks the authority to change a sovereign country's laws or political system. It added that it remains in touch with the Olympic community of Iran.