The U.S. Embassy in Riyadh has canceled consular services for Sunday and Monday in the Saudi Arabian cities of Riyadh, Jeddah and Dhahran because of heightened security concerns.
In a statement issued Saturday, the embassy said the telephone lines would not be open either on March 15-16.
Fox News, citing an intelligence source, said the threat was serious enough that the facilities would have only essential staff over the next two days.
The embassy advised U.S. citizens to cancel all nonessential trips to Saudi Arabia and be extra cautious when traveling through the country .
The statement did not specify reasons for the extra precaution. It advised all Americans to avoid crowds, identify safe areas and prepare for emergencies while in Saudi Arabia.
The State Department did not immediately respond to a request for comment on the embassy statement or the Fox News report.
On Friday, the embassy warned that Western oil workers in Saudi Arabia might be the target of militant attacks. The message did not identify the militants.
Some information for this report came from Reuters.