Search efforts, aided by Italy's Coast Guard, were under way and the Air Force declined to offer many details.

It said only that it "lost contact" with the F-16 at about 8 p.m. local (2100 GMT) - language often used to describe a possible crash, although Air Force officials declined to speculate about the incident.

"The aircraft was performing a training mission over the Adriatic Sea with one person on board. The pilot's condition is unknown at this time," the Air Force said in a statement.

Italy's Coast Guard confirmed it was helping in the search-and-rescue effort.

A spokeswoman at Aviano Air Base in northern Italy said more information would released as it became available