The U.S. Embassy in Saudi Arabia warned Americans on Wednesday that a terrorist group may be planning to abduct Westerners in the capital of Riyadh.
"The U.S. Embassy in Riyadh reminds all U.S. citizens to exercise prudence and enhanced security awareness at all times," the embassy said in a message posted on its website.
The message offered no specifics about the possible abduction plot but simply advised U.S. citizens in Saudi Arabia to follow security procedures, including varying travel routines and avoiding large crowds.
Saudi Arabia has waged a heavy crackdown on Islamist militants since al Qaeda's Saudi branch launched a wave of attacks in the country in 2003, including suicide bombings and shootings that killed dozens of Saudis and foreigners. At least 11 Americans were among the dead.
The kingdom's security forces appeared to have largely crushed the militants by 2006, arresting or killing most of its known leaders.
Last year, the Saudis arrested nearly 100 suspected al Qaeda militants but there is growing concern the terrorist group could use their base in Yemen to ramp up attacks in the kingdom.
On Monday, the former chief of Saudi intelligence services said the kingdom's sizable oil installations were safe despite the growing threat of terrorist attacks in the region.
Prince Turki al-Faisal said the unrest in the Arab world would not spill over into Saudi Arabia.
"While the general picture of Saudi Arabia's surroundings is predominated by this great turmoil, at the center of these many storms sits our Kingdom, which, I am glad to report, remains stable and secure," he said.