The State Department's travel warning for Libya also advised Americans to exercise caution while traveling in Libya.

The U.S. lifted restrictions on the use of U.S. passports for travel to Libya in February 2004 after Tripoli abandoned its program for weapons of mass destruction.

Since then Libya has taken steps to cooperate in the global war on terrorism, but the Libyan government remains on the U.S. government's state sponsors of terrorism List.

"Although Libya appears to have curtailed its support for international terrorism, it may maintain residual contacts with some of its former terrorist clients," the State Department warned.

Most U.S. economic sanctions on Libya ended in September, but credit cards and checks from U.S. banks generally are not accepted in Libya.