An Iranian prisoner on death row has died of cardiac arrest caused by the stress of imminent execution, a rights group reported.

Milad Bahmanzadeh, who had been convicted of murder and sentenced to death, died of a heart attack in Tabriz prison northwest of Iran because of the huge stress and anxiety of his possible execution, Hengaw Organization reported.

Bahmanzadeh lost his life on Sunday, hours after he was transferred to the special ward where prisoners on death row are held.

Over the past few weeks, the Islamic Republic has hanged dozens of prisoners, including protesters, as part of an execution spree widely condemned by the international community.

The number of executions in Iran started to rise after President Ebrahim Raisi – the former head of the country’s notorious judiciary -- took office in August 2021 but the recent exponential spike has triggered concern at home and abroad.

The United Nations said earlier this month that Iran has executed 209 people so far this year, calling the record "abominable". The number has further grown in recent days, particularly with the regime's execution of three political prisoners Majid Kazemi, Saleh Mirhashemi and Saeed Yaghoubi.

Last week Amnesty International condemned the execution spree, and said it "opposes the death penalty in all cases without exception, regardless of the nature or circumstances of the crime; guilt, innocence or other characteristics of the individual; or the method used by the state to carry out the execution."