A group of prominent Iranians with links to football have called on Fifa’s president, Gianni Infantino, to condemn the killing and arrest of footballers and the threats made against players in the country. The demand was made in open letter also addressed to the presidents of Fifa’s 200-plus national associations.

Among its 20 signatories are Ali Karimi, who played 127 times for Iran, and three other former full internationals. The list also includes a coach, a referee and sports journalists.

The letter says a “nationwide, popular, and civic movement” has been met by the Iranian authorities with “systematic repression, mass killings, and actions that constitute clear instances of crimes against humanity and war crimes”.

Among thousands killed in protests this month – the letter refers to information and reports that put the death toll at more than 18,000, though some estimates are even higher – were what the letter describes as “a significant number of members of the football community”. It names among them Mojtaba Tarshiz, a former top-division player, who had two young children.

Other victims listed include Saba Rashtian, a women’s football assistant referee, the youth coach Mehdi Lavasani, the footballers Amirhossein Mohammadzadeh and Ribin Moradi, and Mohammad Hajipour, a goalkeeper for Iran’s beach soccer team.

The letter also raises concern over the fate of Amirhassan Ghaderzadeh, a 19-year-old player with Sepahan Isfahan. His family has reportedly been told he faces an imminent risk of execution because of his participation in protests. His case was condemned by the US state department last week after being highlighted by Amnesty International.

Signatories of the letter, who include a second Iran player picked for the World Cup in Bakhtiar Rahmani, say a nationwide shutdown of internet and telephone communications has made it difficult to verify deaths and arrests. They say several members of the football community have been arrested upon entering Iran for expressing their opinions and have had their passports confiscated.

Addressing Infantino, the letter says: “Football, as the most influential social phenomenon in the world, cannot and must not remain silent in the face of executions, killings, arbitrary arrests, and threats against athletes.”

The group call on Fifa and the national football federations to publicly condemn those actions, demand an immediate halt, use all available legal and disciplinary mechanisms to protect Iranian football figures and “affirm that peaceful protest and the expression of personal opinions are fundamental human rights”.

The letter concludes: “Silence in the face of these crimes amounts to abandoning the very principles that global football claims to defend.”

Fifa has been approached for comment.

Karimi has become one of the most prominent sporting voices supporting Iran’s protest movement. In 2022, he accused the authorities of trying to kidnap him and claimed his family had been threatened after he publicly supported anti-government protests. Karimi, who played for Bayern Munich, moved to the US in 2023 after Iranian security forces briefly seized his family home.

Karimi said Iranians had paid “heavy prices, such as their lives and their freedom” for basic rights over decades and that his aim was to ensure the international community hears about the crimes being committed.

“I have always considered myself one of the people,” he said. “Now that our country is going through one of its most sensitive and sorrowful periods, the least I can do is be the voice of my people.”

Karimi said the protesters were “more hopeful than ever” and that “freedom and democracy through the ballot box” were what they wanted. “We witnessed the mass killing of people, the real numbers of which are far higher than the figures that are announced.”

At least 22 athletes from other sports, including basketball, rock climbing, wrestling and taekwondo, have been killed for taking part in the protests. Massoud Zatparvar, a two-time World Classic Bodybuilding champion, died during protests in the city of Rasht in Gilan province in northwestern Iran. “We only want our rights, the voice that has been stifled for 40 years must be shouted out,” he wrote in his last Instagram post on an account since deleted.

It is understood Iranian authorities are using CCTV footage from shops to compile evidence against those who took part in the protests. The deaths of prominent athletes are often given widespread coverage in the state-run media.

“All they try to do is to create fear,” said one source in Iran who did not want to be named. “They want to say: ‘This is what we do to the athletes, this is what we do to the celebrities, this is what we do to the biggest names. What do you think we can do to you?’”