A former psychologist has been executed for heresy in Iran after eight years in detention, human rights groups said, in the latest example of what activists say is a worrying rise in the use of death penalty by the Islamic Republic.

Mohsen Amir Aslani was hanged for "corruption on earth and heresy in religion," said the Human Rights Activists News Agency, which is based outside Iran. It said the execution took place in a prison near the city of Karaj, west of Tehran on Sept. 24.

Iranian opposition news websites have said Aslani, 37, had given religious classes where he propagated a new interpretation of the Koran. He was also accused by the authorities of insulting the Prophet Jonah.