Earlier this month, a suspected Nato bomb exploded as a fishing net was being hauled on board a boat off Venice, injuring three members of the Italian crew.

Some fishermen have stopped setting out for parts of the Adriatic deemed at risk for bombs.

Mechanical problems can force Nato pilots to dump their bombs prematurely.

The major Aviano air base is close to Venice and it is standard practice to jettison weapons if a military plane is in difficulty as it comes in to land.

Nato says it is safer to drop these bombs at sea, where they can be picked up later by naval vessels, than risk a land explosion.

Mine-sweepers have been searching the waters off Venice trying to find bombs before fishermen haul up more in their nets and Italian Prime Minister Massimo D'Alema will meet the fishermen on Monday.