U.S. citizens living in a residential compound in western Saudi Arabia (search) have been put on high alert after the American Embassy issued an increased threat level warning, officials said Thursday.

The warning singled out the Sierra Village (search), on the outskirts of Jiddah (search), a Red Sea coastal city where tensions remain high following a Dec. 6 attack on the U.S. consulate by Islamic militants.

"Official Americans are relocating to an alternate location as a result of this threat," according to a statement posted on the U.S. Embassy's web site. An Embassy official confirmed the statement but declined to elaborate on the threat.

A Sierra Village employee said the situation is calm in the compound despite the warning, which she said was issued Tuesday following an altercation a day earlier between security guards and youths in a car parked nearby.

"The guards asked the youths what they were doing, and one said 'it's none of your business' before the car sped off," the employee told The Associated Press in Egypt in a telephone interview. She spoke on condition of anonymity.

The employee added that the compound, which houses about 1,000 Westerners, including many Americans, has "very high security" and there was no immediate threat.

The embassy statement urged Americans living and working in the area to "maintain a heightened level of vigilance and continue varying times and routes when traveling."

Saudi Interior Ministry spokesman Mansour al-Turki said security authorities had no specific information of terrorist acts.

The Jiddah U.S. consulate attack led to a gun fight between militants and security forces that killed five foreign consulate employees and four attackers.

Saudi Arabia's image was battered after the Sept. 11, 2001, terrorist attacks carried out by 19 airplane hijackers, 15 of whom were Saudis.

For nearly two years, Saudi Arabia has been waging a crackdown to root out terrorism after al-Qaida-linked militants attacked three residential compounds in Riyadh in May 2003.