Ayoub Karimi was first convicted in 2018 on the capital charge of "corruption on earth" in a case involving six other Kurdish men who also received the death penalty.

They were accused of belonging to illegal groups as well as over links to the cleric's killing in the western Iranian city of Mahabad.

Karimi was hanged along with six other men, who had received sentences in unrelated cases, in Ghezel Hesar prison in the Tehran suburb of Karaj, the Norway-based Iran Human Rights (IHR) group said.

"The execution of Ayoub Karimi, based on coerced confessions and without a fair trial, like the execution of other political prisoners, is a crime," said IHR director Mahmood Amiry-Moghaddam.

The execution was also confirmed by the US-based Human Rights Activists News Agency and France-based Kurdistan Human Rights Network.

Amnesty International had urged Iran not to execute Karimi and said he and his co-accused were convicted in "grossly unfair trials marred by claims of torture to extract 'confessions'."

Rights groups warn that five of the co-accused in the case remain at risk of execution while one of the men, Ghassem Abesteh, was executed earlier this month. They were all arrested in early 2010.

Iran has stepped up executions in recent months after a wave of protests last year triggered by Mahsa Amini's death in custody.

This month it has executed Milad Zohrevand, a man in his 20s in a case related to the protests, as well as 17-year-old youth Hamidreza Azari on murder charges as well as dozens of others.

The UN Human Rights Office on Tuesday condemned both executions.

Activists say that the use of the death penalty disproportionately targets members of the Kurdish and Baluch ethnic minorities in western and southeast Iran, who generally adhere to the Sunni strain of Islam rather than the Shiism otherwise dominant in Iran.