The U.S. Embassy issued an unprecedented emergency security warning to Americans living in Beijing Thursday after the Chinese government learned of a threatened terrorist attack against U.S. citizens in the capital, officials said.

The nature of the threat was not fully clear, but U.S. officials were advised by a "high-ranking representative" of the Chinese government that it stemmed from a group of foreigners, a senior embassy security officer said."There is information from Chinese sources that a small group of individuals was interested in inflicting physical harm on American citizens in Beijing," he said. "We are taking it seriously."

In Washington, a White House spokesman confirmed that Chinese officials did convey "the possibility of a terrorist threat" against Americans.

Roman Popadiuk, deputy White House press secretary, said no details were available, but added, "The Embassy (n Beijing) is taking appropriate precautions."

Administration officials would only identify the alleged terrorists as "Middle Eastern types."

The warning shocked Beijing's small American community. Embassy officials called a snap meeting with about 50 residents to advise them while the American Club of Beijing began a telephone campaign to alert U.S. citizens.