It did not identify the source of the threats and said no details were available on the planned attacks.
The latest was last month when US defence contractor Vinnell Arabia said two of its American employees were shot at in Eastern Province, where most of the kingdom's oil wealth is concentrated. Saudi police said that one of them was wounded but results of the investigation that followed have not yet been revealed. In October, another Vinnell employee was shot dead and another wounded at a petrol station in Riyadh, in what Saudi authorities have said was not a "terrorist-related" incident.
Further, a Dane was wounded in November last year as he was driving away from his workplace when he was fired upon from another car. Authorities said the three Saudis arrested on suspicion of involvement in that attack had acted "in support of" ISIL. A week after the Dane's shooting, a Canadian was stabbed and wounded while he shopped at a mall on Saudi Arabia's Gulf coast.
Several Westerners in Saudi Arabia were killed in a wave of al-Qaeda attacks between 2003 and 2006.