On a sweltering morning, hundreds of black-clad officials, students and survivors laid flowers at the memorial cenotaph, with the ruins of a domed building in the background, a stark reminder of the horrors that unfolded.

Mayor Kazumi Matsui called on leaders to heed the lessons of Hiroshima and Nagasaki and warned of the consequences of the global trend towards a military buildup.

Kazumi Matsui said the conflicts in Ukraine and the Middle East meant a growing acceptance of nuclear weapons.