One of the nation's largest groups representing survivors of the 1945 atomic bombing of Hiroshima and their children will be disbanded at the end of March because its elderly members are finding it too hard to keep the group going, members said Monday.

The roughly 500 members made the decision at an extraordinary board meeting Sunday. The vote was close, but with many leaders now in their 80s and 90s, the move marks the passage of time.

The group represents people exposed to radiation from the bombing, called hibakusha, and living in Fukuyama, Hiroshima Prefecture, as well as their second-generation descendants.

The group is one of the largest in the Hiroshima division of the Japan Confederation of A- and H-Bomb Sufferers Organizations, known as Nihon Hidankyo.

Members have been discussing whether to maintain the association since November due to the poor health of its board members, and the dissolution was decided by a vote of 12 to 11 at Sunday's meeting.

"The very narrow margin is an indication of our feeling," said Toshihiko Sato, the group's 73-year-old secretary general.

"We do not want to dissolve (it), but it can't be helped," he said after efforts to have the second-generation members take over the running of the group ended in failure.

The group has organized a memorial ceremony for atomic bomb victims every year. It has maintained a list of the dead and has been responsible for a cenotaph in Fukuyama. It plans to talk to the municipal government about handing these tasks over.