The injured man is an employee of the Defense Department who was temporarily assigned to the embassy in Amman, the official told reporters on condition of anonymity.

State Department spokesman Richard Boucher declined to provide any details about the man's job or go beyond the basics of the incident, which occurred late Tuesday, but noted that the embassy and Jordanian authorities were both investigating the matter.

"There was a single shot, we understand, was fired from a passing car at an American citizen last evening shortly after he had left his hotel," he said. "He suffered a minor injury, did not require hospitalization."

"The embassy has issued a warning message to all Americans to avoid drawing attention to themselves and take prudent steps to ensure their personal safety," Boucher said.

He could not say whether the injured man had been following the embassy's guidelines for behavior.

Earlier in Amman, Jordanian sources said the man had been walking in the street near a five-star hotel in the Jebel Amman district when one or more people fired at him.

The American was either injured on the ear or on his forehead, according to the sources.

Jordanian Information Minister Mohamad Adwan said police were investigating the reported shooting but stressed that there was no "proof of any foul play" and noted that no bullets had been found.

The senior US official said the injured man had definitely heard a gunshot but could not say whether the wound had been caused by a bullet.

The incident recalled fears of attacks on Americans in Jordan that were sparked by the murder last October of US diplomat Laurence Foley, who was shot dead outside his Amman home.

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