NAGASAKI, Japan (AP) _ American politicians who defend the atomic bombings of Hiroshima and Nagasaki have offended victims with their heartless comments, Nagasaki's mayor told an international disarmament conference Monday.

Mayor Itcho Ito spoke at the opening of a five-day U.N.-sponsored conference, being held in one of the only two cities ever to suffer an atomic attack.

His comments reflected the intractable U.S.-Japan dispute about whether the atomic bombings were necessary to end World War II and provided another reminder of how sensitive war issues remain in Japan 50 years later.

Last week, Japanese lawmakers approved a resolution expressing remorse for Japan's actions in the war, but their failure to give a direct apology angered Asian nations and led to anti-Japanese protests in South Korea.

The United States dropped an atomic bomb on Nagasaki on Aug. 9, 1945, three days after its first bomb hit Hiroshima. About 140,000 people were killed in Hiroshima and 70,000 in Nagasaki.

``The statements by high American officials justifying the atomic bomb are extremely unfortunate,'' Ito told the conference. ``These heartless statements wound the souls of victims who lost family and friends and suffer themselves from atomic aftereffects.''

President Clinton said earlier this year that President Truman's decision to go through with the nuclear attack was correct ``based on the facts he had before him.'' That echoes the view held by many Americans that the atomic bombings saved lives by making a land invasion of Japan unnecessary.

The issue has become increasingly sensitive. Last November, the U.S. Postal Service unveiled a stamp picturing a mushroom cloud and the caption ``Atomic Bombs Hasten War's End,'' but withdrew it after strong Japanese protests.

And in January, the Smithsonian Institution canceled an exhibition on the atomic bombings after U.S. veterans complained it portrayed the United States as an aggressor.

``We are aware that the atomic bombs were dropped in the course of a war that was started by Japan,'' Ito said. ``But nonetheless I want to repeat: the atomic bomb should absolutely not have been used.''

The comments to the conference, an annual event attended by representatives of 35 countries, were Ito's first on an international stage since he was elected mayor in April. He defeated 16-year incumbent Hitoshi Motoshima, who survived an assassination attempt in 1990 after he said Emperor Hirohito bore some responsibility for World War II.

Ito's address was followed by an emotional appeal from bomb survivor Sakue Shimohira, 60, who described how she found her mother's charred body and saw her brother die three days after the bombing.

``Even today, 50 years later, many atomic bomb victims still live in suffering from wounds to body and soul,'' she said. ``We must rise up and pool our wisdom to abolish nuclear weapons.''

Participants said that goal is more possible now than it seemed during the Cold War, especially since the United States and Russia agreed to eliminate dangerous classes of nuclear weapons in the START II treaty.

But several Japanese speakers indirectly criticized the five acknowledged nuclear powers _ the United States, Russia, Britain, France and China _ for failing to disarm more quickly.

The Nuclear Non-Proliferation Treaty, which was extended indefinitely last month, permits those five nations to have atomic arsenals but says they should work toward eliminating nuclear weapons. A nuclear test ban is also supposed to be concluded by next year.