Nobel Peace Prize winner Nihon Hidankyo is a group of survivors of the US nuclear bombings that virtually obliterated the Japanese cities of Hiroshima and Nagasaki at the end of World War II.

The Japanese grassroots anti-nuclear organisation was established in 1956 and is the only nationwide association of A-bomb survivors, who are known as hibakusha.

It has long been tipped for the Nobel for its calls to abolish nuclear weapons, including through powerful testimonies from its dwindling number of aged members, recounting the horror of the attacks.

Japan remains the only country hit by atomic weapons in wartime and next year is the 80th anniversary of the bombings.

Nihon Hidankyo says it stands for the "prevention of nuclear war and the elimination of nuclear weapons, including the signing of an international agreement for a total ban".

It argues that Japan should acknowledge its responsibility of "having launched the war, which led to the damage by the atomic bombing" and therefore provide survivors with compensation.

On August 6, 1945, the first nuclear bomb was dropped on Hiroshima, flattening the city and leaving some 140,000 people dead, either instantly or in the weeks that followed.

Three days later, a second US bomb hit Nagasaki, killing around 74,000.

All members and officials of Nihon Hidankyo are hibakusha, which says it represents almost all the organised survivors in Japan.

There are currently around 106,800 hibakusha in the country, according to the government. Their average age is 85.

Nihon Hidankyo works to tell survivors' stories, to convey the damage and after-effects of the attacks.

The group has also sent survivors to the United Nations and countries that hold nuclear weapons, and provides counselling and other assistance to survivors.

After then-US president Barack Obama won the Nobel Peace Prize in 2009, he met and embraced atomic bomb survivors on a historic visit to Hiroshima. (AFP)