Mehrab Abdollahzadeh had been arrested in connection with months-long demonstrations which broke out in September that year following the death in custody of Mahsa Amini, according to state television.

Amini, a 22-year-old Iranian Kurd, had been detained by Iran's morality police for allegedly violating the Islamic republic's dress code for women.

"Mehrab Abdollahzadeh's death sentence was carried out this morning after completing the legal formalities," said the Iranian judiciary's Mizan Online website.

He had been convicted of the capital offence "corruption on earth", while two other defendants in the case below 18 years of age were sentenced to imprisonment of unspecified terms, Mizan added.

Abdollahzadeh, along with the others, was arrested at the scene of street protests in the northwestern city of Urmia, where a farmer "was severely beaten by rioters and tragically martyred", the judiciary said.

The farmer was attending the protests "as a volunteer force to ensure the security of the people", according to Mizan.

The website published what it said was part of a confession by Abdollahzadeh in which he admitted to "hitting the officer several times in the face".

The months-long protests following Amini's death shook Iran, with hundreds of people, including dozens of security personnel, killed, and thousands of demonstrators arrested.

Iranian authorities labelled the protests "foreign-instigated riots".

In recent weeks the government has carried out multiple executions of people linked to a separate round of mass protests earlier this year, which peaked in January before the war with the United States and Israel broke out on February 28.

Those demonstrations began in late December over rising living costs before spreading nationwide and evolving into huge anti-government protests that peaked on January 8 and 9.

Iranian authorities labelled those rallies "foreign-instigated riots" as well, saying they involved killings and vandalism.