The Group of Seven meeting has published the Hiroshima Declaration to call for a "world without nuclear weapons", after the ministers paid a landmark visit to a Japanese atomic bomb memorial.

The statement came as ministers wrap up their final day of meetings with discussions on global hotspot issues, including terrorism, instability in the Middle East, and the refugee crisis.

John Kerry has become the first US secretary of state to visit Hiroshima's atomic bomb memorial. He called it a "stark, harsh, compelling reminder" to end the threat of nuclear weapons. But he avoided talking about the history of the bombing by the US during World War Two, saying this trip is not about the past, but the present and the future.