Nagasaki marked the 74th anniversary Friday of the atomic bombing of the city, with Mayor Tomihisa Taue using the memorial ceremony to call on the government to immediately sign a U.N. treaty banning nuclear weapons.

"As the only country in the world to have experienced the devastation caused by nuclear weapons, Japan must sign and ratify the Treaty on the Prohibition of Nuclear Weapons as soon as possible," Taue said in the annual declaration.

The mayor had urged the central government to sign the international treaty at the two previous annual ceremonies, but this year he used stronger and more direct language.