Hiroshima marked the 78th anniversary of the city's atomic bombing by the United States on Sunday after its nuclear legacy took center stage when it hosted the summit of the Group of Seven major economies in May.

In his annual Peace Declaration delivered at the ceremony in the Peace Memorial Park, Mayor Kazumi Matsui hailed the G7 leaders' historic visit to the park and its atomic bomb museum as proof that the "spirit" of Hiroshima reached them, while urging policymakers to abandon the theory of nuclear deterrence.

"Leaders around the world must confront the reality that nuclear threats now being voiced by certain policymakers reveal the folly of nuclear deterrence theory," Matsui said, adding, "They must immediately take concrete steps to lead us from the dangerous present toward our ideal world."