Mexico City is the birthplace of the Treaty of Tlatelolco, the world's first nuclear-free zone agreement applied in Latin America in 1969.

Jody Williams, who was awarded the Nobel Peace Prize in 1997 for her work against landmines, was also at the conference.

'Nuclear weapons are a danger to international peace and security, an intolerable threat to the very survival of our species,' Mexican Foreign Minister Patricia Espinosa said at the conference.