US diplomatic officials based in Saudi Arabia say they are suspending operations at the embassy and consulates in the kingdom due to "heightened security concerns", Press TV reported.
The US embassy officials in Riyadh said in a statement issued early on Sunday that telephone lines at the diplomatic facilities will be disconnected on Sunday and Monday and called on Americans in the kingdom to "be aware of their surroundings and take extra precautions when travelling throughout the country."
The statement neither identified a precise security threat nor did it call for the complete evacuation of the diplomatic facilities.
The US consulate generals in Saudi Arabia are located in the Red Sea city of Jeddah and in Dhahran in Eastern Province.
The State Department has also called on American citizens to "carefully consider the risks of traveling to Saudi Arabia and limit non-essential travel within the country."
"Regardless of where you are, it is always advisable to keep your security and situational awareness levels high," it added.
On Friday night, the US embassy in Saudi Arabia said in a warning posted online that Western oil workers in the country are at risk of being attacked or kidnapped by "terrorist" groups.
The embassy said it "has information stating that, as of early March, individuals associated with a terrorist organization could be targeting Western oil workers, possibly to include those US citizens working for oil companies in the Eastern Province, for an attack(s) and/or kidnapping(s)".
Several people from the US and Europe were killed in a spat of deadly attacks conducted by al-Qaeda in Saudi Arabia between 2003 and 2006.