Survivors of the 1945 U.S. atomic bombing of Hiroshima and Nagasaki have strongly welcomed Friday's adoption of a treaty banning nuclear weapons after months of negations at the United Nations, while some criticized Japan for not joining the initiative.

"I have been waiting for this day for seven decades and I am overjoyed that it has finally arrived," Setsuko Thurlow, 85, said during the conference in New York where the legally binding pact outlawing nuclear weapons was agreed. "This is the beginning of the end of nuclear weapons."

Thurlow was 13 years old when she witnessed the first bomb drop on Hiroshima in western Japan on Aug. 6, 1945. As a survivor, known in Japanese as "hibakusha," she has become an advocate of nuclear nonproliferation.

A total of 122 countries on Friday gave their blessing to the treaty whose preamble referred to the "unacceptable suffering" of victims of the atomic bombings of Hiroshima and Nagasaki.

Thurlow urged governments to ratify the pact to help achieve a world free of nuclear weapons. The treaty will enter into force 90 days after being ratified by 50 nations.

Separately, Toshiki Fujimori, assistant secretary general of the Japan Confederation of A- and H-Bomb Sufferers Organizations, known as Nihon Hidankyo, hailed the adoption of the treaty.

"I never would imagine this treaty was going to be concluded on July 7," he told reporters. "I think it is the collective effort of the humanity of all the people that came together here at the United Nations."

Kunihiko Sakuma, 72, who heads the Hiroshima chapter of Nihon Hidankyo, also welcomed the initiative, saying, "It became a big step for nuclear abolition."

Referring to a reference to the suffering of A-bomb victims in the pact's preamble, Sakuma said, "The devastation of the atomic bomb exposure became known to people around the world and this moved many countries to believe that nuclear weapons must be abolished."

Meanwhile, Nagasaki Mayor Tomihisa Taue called the move "a historic moment" but expressed disappointment over Japan not joining the treaty, as it is among the nations that rely on U.S. nuclear deterrence for protection.

"It is very regrettable to the A-bombed area that the Japanese government was not involved" in the pact, Taue said in a statement.

Hiroshima Mayor Kazumi Matsui called on nuclear powers and Japan to sign the treaty in the future to make it effective.

"In order to make the pact effective, we need to encourage all countries to conclude the treaty," Matsui told a press conference.

"We'd like to create an environment in which the Japanese government can accept Hiroshima's feelings and act with courage," he said.

A-bomb survivor Tadako Kawazoe, 73, who listened to a meeting among negotiators at the U.N. headquarters in June, voiced hope for Japan's participation in the future.

"How citizens will act will be important to motivate (the government) to join the pact in the future," Kawazoe said.

Takao Takahara, director of the International Peace Research Institute at Meiji Gakuin University, called the treaty "very significant," as it not only refers to the suffering of survivors but also recognizes their long-time efforts to prevent the use of nuclear weapons.

As the world still faces a high risk of a nuclear accident or accidental nuclear war, Japan has the role of stressing the inhuman aspect of nuclear weapons to countries which have not joined the Nuclear Non-proliferation Treaty and nuclear powers, he said.

But Hirofumi Tosaki, senior research fellow of the Center for the Promotion of Disarmament and Non-Proliferation of the Japan Institute of International Affairs, expressed doubt over the treaty's effectiveness.

"To steadily promote nuclear arms reduction, discussions and cooperation with nuclear powers and countries under the 'nuclear umbrella' that did not join the talks will be imperative," Tosaki said.