"We reaffirm our commitment to seeking a safer world for all and to creating the conditions for a world without nuclear weapons in a way that promotes international stability," the group said in their "Hiroshima Declaration", after a landmark visit to the Japanese city's atomic bomb memorial.

"This task is made more complex by the deteriorating security environment in a number of regions, such as Syria and Ukraine, and, in particular by North Korea's repeated provocations," it added.

On Saturday, Pyongyang said it had successfully tested an engine designed for an inter-continental ballistic missile (ICBM) that would "guarantee" an eventual nuclear strike on the US mainland. It was the latest in a series of claims by North Korea of significant breakthroughs in both its nuclear weapons and ballistic missile programmes.

The G7 statement came as ministers wrap up their final day of meetings with discussions focused on global hotspot issues including terrorism and other security threats as well as instability in the Middle East, and the refugee crisis.

- AFP