Tokyo: Japanese PM Shinzo Abe and Nagasaki Mayor on Monday were among several delegates attending the ceremony to mark 70 years since an atomic bomb was dropped at the southern Japanese city on August 9 1945.
At least 70, 000 souls were killed when the US dropped a plutonium bomb named "Fat Man" at 11:02 am on Nagasaki, just three days after a bombing on Hiroshima had killed 1,40, 000.
To mark the tragic moment, bells tolled in Nagasaki and a minute's silence was observed at 11: 02 am by survivors and victims' kin
The ceremony held at Nagasaki Peace Park started with children reading a declaration.
The ceremony was also attended by delegates from 75 countries including US envoy Caroline Kennedy who gathered under a tall white canopy to shade them from the sun on a 31-degree-Celsius (88-degree Fahrenheit) morning at Nagasaki Peace Park.
The main highlight of the ceremony was how a speech by a survivor and also Nagasaki Mayor Tomihisa Taue slammed PM Shinzo Abe's new legislation limiting Japan's military to self defence.
Delivering a peace declaration to the ceremony, the mayor expressed there was "widespread unease" about Mr Abe's legislation that will alter the constitutional requirement limiting Japan's military to self defence.
The Mayor urged the government to ensure that it went through "sincere and careful deliberation" before going ahead with the laws.
A survivor of the Nagasaki attack, 86-year-old Sumiteru Taniguchi, who recounted the deadly trauma by showing his 70-year-old scars, said he could not accept Mr Abe's new legislation.
Meanwhile, Abe in his statement said that Japan remained "determined to pursue a world without nuclear weapons".
UN Secretary General Ban Ki-moon delivered a strong statement saying, "Nagasaki must be the last - we cannot allow any future use of nuclear weapons. The humanitarian consequences are too great. No more Nagasakis. No more Hiroshimas."