Ceremony in peace park near epicentre of world's first atomic attack attended by 50,000, including Harry Truman's grandson.
Japan marked the 67th anniversary of the first atomic attack with a ceremony on Monday that was attended by a grandson of Harry Truman, the US president who ordered the bomb to be dropped on the city of Hiroshima.
About 50,000 people gathered in Hiroshima's peace park near the epicentre of the 1945 blast that killed as many as 140,000 people. A second atomic bombing on 9 August in Nagasaki killed tens of thousands more and prompted Japan to surrender, bringing the second world war to an end.
The ceremony, attended by representatives of about 70 countries, began with the ringing of a temple bell and a moment of silence. Flowers were placed before Hiroshima's eternal flame.
Truman's grandson, Clifton Truman Daniel, and the grandson of a radar operator who was on both of the bomb run planes, joined in the memorial. Ari Beser's grandfather, Jacob Beser, was the only person who took part in both the Hiroshima and Nagasaki bombings.
In a news conference after the memorial, Daniel declined to comment on whether his grandfather's decision was the right one.
"I'm two generations down the line. It's now my responsibility to do all I can to make sure we never use nuclear weapons again," he said, according to Japan's Kyodo news service.
Daniel, 55, said in a statement earlier that he decided to visit Hiroshima and Nagasaki because he needed to know the consequences of his grandfather's decision as part of his own efforts to help achieve a nuclear-free world.Hiroshima's mayor, Kazumi Matsui, said Japan must take a bolder role in leading global disarmament efforts and called on world leaders to come to his city to "contemplate peace".
He also said the nuclear accident at Fukushima last year has shown the dangers of nuclear technology, even for peaceful purposes, and urged the government to create a mix of energy sources for Japan that is safe and secure.