The US Embassy in Riyadh and two other diplomatic missions in Saudi Arabia have cancelled all consular services for two days over security fears.
The embassy said it and missions in Jiddah and Dhahran will provide no consular services today and tomorrow due to "heightened security concerns". It did not elaborate.
The move follows a warning by the embassy citing information about a threat by militants to kidnap Western oil workers, including Americans, from oil fields in the kingdom's Eastern province.
From 2003 to 2007, al Qaida-linked militants carried out attacks in Saudi Arabia aimed at destabilising the Western-allied monarchy, including deadly bombings of residential compounds housing foreigners in Riyadh in 2003.
The kingdom now is taking part in the US-led coalition against the Islamic State group.