Nagasaki (AsiaNews/Agencies) - Nagasaki called on world leaders today to conclude a treaty banning nuclear weapons at a ceremony marking the 67th anniversary of 'Fat Man,' the codename for the atomic bomb that destroyed the city (the bomb that devastated Hiroshima on 6 August was codenamed 'Little Boy'). "The international community must act now by taking the first concrete steps toward concluding the Nuclear Weapons Convention," Mayor Tomihisa Taue said. He also expressed his city's solidarity with the victims of last year's Fukushima nuclear disaster, survivors as well as relatives now facing hardships.

In his address, Mayor Taue also called on the central government to address the "serious challenge" presented by North Korea's nuclear arms threat. In a speech, Prime Minister Yoshihiko Noda declared that Japan has a "responsibility" to encourage countries and the international community to eliminate their nuclear arsenals.

For the first time, US Ambassador John Roos attended the ceremony along with representatives from about 40 countries. Roos did attend Hiroshima's annual peace ceremony before, but never Nagasaki's. Both mark the atomic bombs dropped by the United States that ended the Second World War in the summer 1945.

In Nagasaki, up to 80,000 people were incinerated in the blast or died from radiation-related illnesses by the end of 1945. The number of officially recognised Nagasaki hibakusha, the surviving victims of the atomic bombings, stood at 39,324 as of March, with an average age of 77 and half years.

In an explicit reference to the March 2011 nuclear disaster in Fukushima, Mayor Taue called for a society "free from the fear of radioactivity." He is the first Japanese mayor to call on Japan to move away from nuclear energy and promote instead new energy sources in place of nuclear power.

Taue also called for action on the radioactive waste that has piled up, and pledged that Nagasaki would "continue to support the people of Fukushima".