WASHINGTON -- The United States says an American citizen may be missing in Yemen.

A State Department official says the U.S. is aware of reports of a missing American but can't discuss any individual's situation. The reports had indicated an oil worker was taken hostage in the capital of Sanaa, currently controlled by Shiite rebels known as Houthis.

The State Department official says the U.S. urges all Americans living in Yemen to leave as soon as they safely can. The official wasn't authorized to comment by name and requested anonymity.

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The State Department says there's a high security threat to Americans because of terrorist activities and armed groups in Sanaa that have detained U.S. citizens before.

A Saudi-led coalition has been fighting the Houthis in Yemen since March 2015.