An Iranian official in the region said on Sunday the authorities had verified at least 5,000 people had been killed in protests in Iran, including about 500 security personnel, blaming "terrorists and armed rioters" for killing "innocent Iranians".

The official, who declined to be named due to the sensitivity of the issue, also told Reuters some of the heaviest clashes and highest number of deaths were in the Iranian Kurdish areas in northwest Iran, a region where Kurdish separatists have been active and where flare-ups have been among the most violent in past periods of unrest.

"The final toll is not expected to increase sharply," the official said, adding that "Israel and armed groups abroad" had supported and equipped those taking to the streets.

The Iranians authorities regularly blame unrest on foreign enemies, including Israel, an arch foe of the Islamic Republic which launched military strikes on Iran in June.

The U.S.-based HRANA rights group said on Saturday the death toll had reached 3,308, with another 4,382 cases under review. The group said it had confirmed more than 24,000 arrests.

The Iranian Kurdish rights group Hengaw, based in Norway, has said some of the heaviest clashes during protests that erupted in late December were in Kurdish areas in the northwest.

Editing by Edmund Blair and Louise Heavens/Reuters