Iran said on Tuesday its security forces had arrested a network of agents working for Israel and had seized a cache of weapons it said were planned for use during recent unrest sparked by water shortages in the Islamic Republic, state media reported.

Iran often accuses its enemies or rivals abroad, such as Israel, the United States and Saudi Arabia, of trying to destabilise the country by stoking protests and violence.

Tuesday's announcement came after nearly two weeks of protests over water shortages, mostly in southwest Iran, which have turned political and spread to other areas.

Authorities have accused armed dissidents of provoking clashes during the street protests. Human rights groups say security forces have opened fire on protesters.

"Mossad operatives intended to use the equipment in urban riots and assassinations," an Intelligence Ministry official said, according to state media, referring to Israel's intelligence agency. The official did not give details.

The seized weapons included pistols, grenades, assault rifles and ammunition, the unnamed official said, adding: "Some of these are used to provoke clashes during protests."

There was no immediate comment from Israeli officials.