U.S. officials said Sunday they will halt operations at the embassy and consulates in Saudi Arabia for the next couple of days, in response to “heightened security concerns.”

Embassy officials in Riyadh issued the statement, saying telephone lines at the facilities will be down Sunday and Monday and encouraging U.S. citizens in Saudi Arabia to “be aware of their surroundings and take extra precautions when travelling throughout the country.”

The message did not cite a specific security concern or threat nor call for the evacuation of the facilities.

However, an intelligence source told Fox News that it was a car bomb threat that triggered the measures, and was serious enough that the facilities will have only essential staff over the next two days.

The U.S. Consulate Generals in Saudi Arabia are in the cities of Dhahran and Jeddah.

In addition to the embassy directive, the State Department is urging U.S. citizens to “carefully consider the risks of traveling to Saudi Arabia and limit non-essential travel within the country.”

The agency also warned: “Regardless of where you are, it is always advisable to keep your security and situational awareness levels high.”

Fox News’ Catherine Herridge and Kara Rowland contributed to this report.