WASHINGTON — The U.S. State Department has issued a travel alert to U.S citizens living in South Africa or traveling there for the World Cup.

"There is a heightened risk that extremist groups will conduct terrorist acts within South Africa in the near future," the department said in an alert Thursday. "While a number of terrorist threats against the World Cup in South Africa have appeared in the media in recent weeks and months, the U.S. government has no information on any specific, credible threat of attack that any individual or group is planning to coincide with the tournament."

The State Department said it would make any information public on "a specific and credible threat."

U.S. citizens were advised to keep car doors and windows locked while driving and not to leave valuables in plain view or to wear expensive jewelry.

The alert said public transportation is "poorly developed" and advised using rental cars or private transport instead. And when stopping at intersections at night or in isolated areas, it suggested leaving room for a "quick exit."

The State Department says its alerts are "about short-term conditions" in a country "that pose imminent risks to the security of U.S. citizens." Its warnings are "to describe long-term, protracted conditions that make a country dangerous or unstable."