Two large caches of bombs, explosives and ammunition, intended for use in "terrorist operations" in public areas, have been found in eastern and western Iran, the Islamic Republic's ministry of intelligence claimed on Wednesday in a statement.
The ministry blamed Saudi Arabia to be somehow involved. Large numbers of Sunnis live in Eastern and Western Iran and there are Sunni groups, who occasionally launch attacks against the Islamic Republic targets.
Both Saudi Arabia and Iran often blame one another for fomenting unrest and supporting militant groups.
The cache found in eastern Iran consisted of 23 remote controlled bombs which were alleged to have been brought across the eastern border with the help of "Saudi intelligence services", the statement, quoted by state media, said.
There was no immediate reaction from Riyadh.
Last June, Islamic State carried out attacks at the Iranian parliament in Tehran and the mausoleum of Ayatollah Ruhollah Khomeini, the founder of the Islamic Republic, south of the capital, which killed at least 18 people.
Iran blamed Saudi Arabia for the attacks, a charge Riyadh denied.
The second cache was found in the town of Marivan in the Kurdish region of western Iran. The cache consisted of TNT, explosives kits, electronic detonators, grenades, ammunition clips for AK-47 machine guns and four rocket propelled grenades, the statement said.
A "terrorist group" brought the material from the Kurdish region of Iraq across the border into Iran, the intelligence ministry statement said, without elaborating.
In recent years, Iranian security officials have made several claims about discovering "terrorist cells" or finding caches of explosives and weapons. But they have never shown any evidence or held public trials of those allegedly arrested.
With reporting by Reuters, Iranian agencies