Italian President Giorgio Napolitano marked the 62nd anniversary of Hiroshima's atomic bombing on Monday, urging the international community to work for peace and disarmament.
Hiroshima, a port in south-west Japan, was largely destroyed on August 6, 1945 when the US dropped the first atomic bomb to be used in warfare.
The US bomber Enola Gay unleashed the bomb which exploded 580 meters above the city, completely destroying a radius of two-and-a-half kilometers and killing at least 78,000 people instantly.
It was never possible to establish an official toll because the radiation caused death, illness and birth defects for years afterwards but by the end of 1945, the number of dead had reached about 140,000.
A second Japanese city, Nagasaki, was hit by an atomic bomb on August 9, 1945.
"We must transmit to the generations who did not live through the Second World War nor through risks connected to the subsequent Cold War period, the recollection of the pain and suffering of the people of Hiroshima and Nagasaki. Until now the international community has succeeded in avoiding a repetition of a similar catastrophe.
Unfortunately, however, the threat remains. Although some types of armaments have been banned, many others are still being stockpiled. Moreover, despite international non proliferation treaties, interest in the development and possession of nuclear weapons is ongoing," the Italian head of state said.
"To avoid another Hiroshima or Nagasaki we must work to ensure that peace and disarmament are not just guidelining principles."