Iranian wrestling champion Navid Afkari has been executed for the alleged murder of a security guard during anti-Government protests in 2018, according to state media.
"The retaliation sentence against Navid Afkari, the killer of Hassan Turkman, was carried out this morning in Adelabad prison in Shiraz," Iranian state television quoted the chief justice of Fars province, Kazem Mousavi, as saying.
Afkari, whose case had attracted global attention and led to the likes of United States President Donald Trump pleading for clemency, had claimed he was tortured into making a false confession.
The 27-year-old had been given two death sentences for stabbing a security guard and his involvement in demonstrations against the country's regime in 2018.
Human rights groups and activists believe he had been unjustly targeted by the Iranian authorities to intimidate others who might choose to participate in peaceful protests.
His death is likely to lead to calls for Iran to face sanctions from the International Olympic Committee (IOC) and other sports organisations.
The IOC claimed its President Thomas Bach had "made direct personal appeals to the Supreme Leader and to the President of Iran this week and asked for mercy for Navid Afkari, while respecting the sovereignty of the Islamic Republic of Iran".
"The execution of wrestler Navid Afkari in Iran is very sad news," the IOC said in a statement.
"The IOC is shocked by this announcement today.
"It is deeply upsetting that the pleas of athletes from around the world and all the behind-the-scenes work of the IOC, together with the NOC of Iran, United World Wrestling and the National Iranian Wrestling Federation, did not achieve our goal.
"Our thoughts are with the family and friends of Navid Afkari."
United World Wrestling, which had not previously commented publicly on the case, said Afkari's execution was "devastating".
"The entire wrestling community mourns his death," UWW added.
Bach said last week he was "extremely concerned" by Afkari's case and claimed the National Olympic Committee (NOC) of the Islamic Republic of Iran and the country's wrestling federation were "doing their utmost to facilitate a solution".
Trump also made a plea for Iran not to execute Afkari.
"To the leaders of Iran, I would greatly appreciate if you would spare this young man’s life, and not execute him," Trump tweeted last week.
Dozens of athletes and officials from several sports spoke out in support of Afkari following the death sentencing, which attracted widespread criticism from across the world.
Afkari's televised confession, which his supporters alleged was coerced, was broadcast by Iran last week.
Critics have said it resembled hundreds of other suspected coerced confessions in the country in recent years.