The US embassy in Saudi Arabia has urged American nationals living in the oil-rich kingdom to "exercise prudence" amid information that they may come under attack, Press TV reported.
The warning, which was posted on the US embassy website, was the first of its kind this year, AFP reported on Saturday.
"We have received credible information that an unidentified extremist(s) in Saudi Arabia may be planning to attack Westerners working and living in Al-Qassim, Saudi Arabia," the message read.
According to the message which was dated August 4, the timing and method of potential attacks are currently unknown.
It also urged Americans to keep "security and situational awareness levels high," and that they change their routes and times to and from work, among other things.
Al-Qassim Province, located in the center of Saudi Arabia and approximately 400 km (249 miles) northwest of Riyadh, is considered the heartland of the Wahhabi fundamentalism.