By Joseph Campbell and Tom Bateman HIROSHIMA, Japan (Reuters) -Exactly 80 years since an atomic bomb was used in war for the first time, thousands bowed their heads in prayer in Hiroshima on Wednesday,

The number of survivors of the U.S. atomic attacks on Hiroshima and Nagasaki is dwindling 80 years later, but they are increasingly speaking out against nuclear weapons.

Hiroshima on Wednesday marked the 80th anniversary of the U.S. atomic bombing of the western Japanese city, with many aging survivors expressing frustration about the growing support of global leaders for nuclear weapons as a deterrence.