Iran has executed more than 500 people so far in 2022, far more than in the whole of last year, the Norway-based group Iran Human Rights told AFP on Monday.

The group said at least 504 people had now been executed in Iran this year and it is still working to confirm additional cases of people said to have been hanged.

The figure comes as concern grows that the authorities will make extensive use of the death penalty against people involved in the anti-regime protests that have erupted in Iran since September.

IHR's count includes four people who official media said were put to death on Sunday after being accused of working with Israel's intelligence service.

The rights group said they were executed in Rajai Shahr prison in Karaj outside Tehran -- also known as Gohardasht -- within just seven months of arrest.

Another of those recently hanged was a woman executed on Saturday in Dastgerd in central Iran accused of murdering her father-in-law, IHR said.

According to its data, at least 333 people were executed in 2021, a 25 percent increase compared to 267 in 2020.

The executions come as widespread riots in Iran, which began after the September 16 death of 22-year-old Mahsa Amini who was arrested by the morality police, continue.

There has long been a concern over the number of executions in Iran, which activists say disproportionately target members of the country’s ethnic and religious minorities, notably Kurds in the northwest, Arabs in the southwest and Baluch in the southeast.