In the presence of Prime Minister Shinzo Abe and U.S. Ambassador Caroline Kennedy, Japan marked the 70th anniversary of the Nagasaki bombings on Sunday.

An estimated 74,000 people died in the initial blast from a plutonium bomb dubbed "Fat Man" dropped on the city on Aug. 9, 1945, and many died from after-effects in the months and years that followed. Nagasaki was bombed three days after Enola Gay, the American B-29 bomber, dropped a bomb called "Little Boy," on Hiroshima, the first atomic bombing in history.

Nagasaki was chosen after a cloud obscured the original target, Kokura.

At the solemn ceremony in front of guests from 75 countries, a declaration was read out by children. This was followed by a minute's silence and bells to mark the time of the explosion in 1945 at 11:02 (02:02 GMT).

Nagasaki mayor Tomihisa Taue delivered a peace declaration to the ceremony and said that there was "widespread unease" about Prime Minister Abe's bid to alter the country's pacifist constitutional, reports the BBC.

Taue called on the government to ensure that "sincere and careful deliberation" took place before it proceeded with the laws, according to Al Jazeera.

During the memorial service, survivor Sumiteru Taniguchi spoke, describing his own terrible injuries, like the skin hanging like rags from his arms and back. Perhaps the most powerful moment in the ceremony came when Taniguchi turned towards Abe and warned him not to meddle with Japan's pacifist constitution. The audience erupted in loud clapping while Abe looked straight ahead, showing no emotion, according to the BBC.

Addressing the ceremony, Abe said Japan remained "determined to pursue a world without nuclear weapons."

In a statement read out on his behalf, UN Secretary General Ban Ki-moon said: "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," reports BBC.