Four people are missing following a crash in which two Italian air force fighter jets collided on a training exercise.

In a statement the Italian ministry of defence said the four crew members are missing following the mid-air collision.

"Rescue helicopters and reconnaissance fighters are in the air and a team of experts have been sent to the accident site," the statement added.

Italian media reported that the two Tornado aircrafts collided near Ascoli Piceno in the Marche region.. 

Witnesses said the two planes had touched in flight before crashing.

Falling debris started a number of fires in the area, although no homes appear to have damaged, according to reports.