Survivors of the atomic bombings of Hiroshima and Nagasaki on Friday presented a petition with nearly 3 million signatures to U.N. officials as a conference to negotiate the world's first nuclear weapons ban treaty got underway.

Toshiyuki Mimaki, 75, and Masako Wada, 73 — survivors, respectively, of the Hiroshima bombing on Aug. 6, 1945, and the Nagasaki bombing three days later — handed over the signatures and an accompanying letter to Costa Rican Ambassador Elayne Whyte Gomez, who serves as chair of the three-week conference that began on Thursday.

A group of hibakusha living in Japan and abroad began a campaign last spring to coincide with the 60th anniversary of the founding of the Japan Confederation of A-and H-Bomb Sufferers Organizations (Nihon Hidankyo).