Beatrice Fihn who is the director of the International Campaign to Abolish Nuclear Weapons, or iCAN, said they posed more of threat now than ever.
Ms Fihn said the risk of world leaders authorising their use was increasing as was the threat from accidents and misunderstandings.
She said the recent North Korean missile false alert in Hawaii demonstrated how quickly things could go wrong.
Ms Fihn said there was also the possibility of nuclear disaster through the effects of climate change.
