Saudi Arabia says an investigation shows that members of an alleged spy ring arrested last week were working for Iran.
An Interior Ministry statement says 18 suspects arrested on March 19 had "direct links" to Iran's intelligence services.
It says physical evidence and detainees' confessions prove the group received money from Tehran in exchange for information about vital locations in the kingdom.
The detained suspects include an Iranian, a Lebanese citizen, and 16 Saudis.
Iran has denied any involvement in espionage in Saudi Arabia.
Based on reporting by AP, AFP, and the Saudi Press Agency