TOKYO - With her knees shaking and her heart thudding, Toshiko Hamamako rose to address the audience. But it was more than stage fright.

Hamamako was just an infant when the U.S. military dropped an atomic bomb on Hiroshima, some 700 kilometers west of Tokyo on Aug. 6, 1945, and on Nagasaki three days later, in order to end the Japanese aggression and the Pacific War. Today, more than 60 years later, she is finally speaking out in public about her life of suffering.

"The experience of standing before an audience and talking about my life for the first time was terrifying but was also an important personal learning experience," Hamamako, now 66, recalled. She had related her story at the Nuclear Non-proliferation Treaty (NPT) conference in New York in May, alongside other ‘hibakusha' or atomic bomb survivors.

Their oral testimonies, recounting horrifying stories of painful illnesses and treatment, continue to be powerful evidence of the devastation caused by nuclear weapons.

But the devastation they suffered was not only about living with radiation burns and medical problems. To this day, Hamamako, others like her and their families suffer from the social fallout of the atomic bomb blasts: stigma and discrimination toward survivors.

"We were considered contaminated and therefore must be avoided," Hamamako explained, adding that even infants in survivor families are stigmatized.

"I told the audience how awful it is to live as a hibakusha," said Hamamako, who now lives in Saitama, a suburb west of the capital Tokyo, with her husband and daughter. "My mother never spoke to me of that time because she did not want to recall the long years of how she and my sister, as well as everybody else around them, suffered. They were so badly affected from radiation burns that never healed."

When they got married, Hamamako's husband had in fact made her promise to keep her ‘hibakusha' status a secret, to protect the family from social discrimination. "I respected his wishes. It was only two years ago that I decided to speak out and I am so glad I did. I realise now how important my story is for world peace," she said.

"I knew I was reaching out to the listeners," 67-year-old Hiroshi Nakamura, another survivor, says of addressing the New York conference Hamamako went to. "My message was far more effective in comparison to books and films on the horrors of the atomic bomb."

These survivors' stories may not about the actual atomic catastrophe because they were too young then, but peace activists say they highlight both the impact of the atomic bombings and the social exclusion that persist decades later.

"People like Hamamako are crucial to the lesson we bring from Hiroshima to the world," explained Prof Mitsuo Okamoto, head of the Hiroshima Centre for Non-violence and Peace. "Their testimonies represent a continuation of the role played by the older generation of survivors, whose stories of that fateful day have galvanized global action for peace," he said.

There are some 162,000 officially-recognized atomic bomb survivors, according to government statistics. More than 60 percent are in their 70s and 80s, and suffer from radiation- related illnesses such as cancer or mental stress.

The uranium bomb dropped by U.S. warplanes over Hiroshima created a huge mushroom cloud of intense radiation, killing 140,000 people, or some 40 percent of the city's residents, on Aug. 6, 1945. In Nagasaki, the toll was just as horrendous: 73,884 people wiped out instantaneously, and another 74,909 injured.

In a survey of 1,500 atomic bomb survivors by the ‘Asahi' newspaper in July, some 61 percent of the younger generation of ‘hibakusha' - those now in their 60s - said they started opening up and telling their stories only after 2005.

For many, their prolonged silence was the result of social stigma they were already going through and fears of reduced chances of marriage, brought on by a fear among many Japanese that the health of children and grandchildren of ‘hibakusha' would be affected by radiation. In fact, Nakamura describes his ‘hibakusha' status as a "death penalty" because he does not know when he could be diagnosed with a radiation-related sickness.

But, this year, Nakamura is heartened by the news that U.N. Secretary-General Ban Ki-moon has decided to attend the ceremony marking the 65th anniversary of the atomic bombing of Hiroshima on Aug. 6. Government representatives from the United States, France and Britain are also expected to be present for the first time in the history of these commemorative events.

"Such steps give us enormous hope to carry on," said Nakamura, who lost his mother - also a ‘hibakusha' - to cancer.

But among the biggest obstacles the ‘hibakusha' face is their fellow Japanese' cold reaction to them.

‘Hibakusha' and their supporters complain that Japanese history textbooks do not discuss the Pacific War and World War II in nearly enough detail - especially Japan's role in the war and its harsh colonization of parts of East Asia.

"There are many times, I feel, that the Japanese feel we are a nuisance because we bring (back) the past of Japan's role in World War II. This makes me sad," said Hamamako. "But I will keep talking."