A 92-year-old man who survived the 1945 atomic bombing in Hiroshima in western Japan has started sharing his experiences with young people.

When the bomb was dropped, Saiki Mikio was 13 years old and at home 2.2 kilometers from ground zero.

He says he had spoken little about the bombing because he felt guilty for surviving while many other students died.

But he says the Russian invasion of Ukraine among other incidents prompted him to change his mind. This month, he became a witness of the bombing named by Hiroshima City at the age of 92.

On Wednesday, Saiki gave his first lecture as a certified witness at the Hiroshima Peace Memorial Museum to 43 elementary school students from Tottori Prefecture.

He said that immediately after the bombing, he saw a number of people who could not open their eyes with skin dangling from their arms. He said those people were walking in search for water.

He noted that after the war ended, many people suddenly lost their hair or died due to leukemia or other diseases.

He said: "People in the world still have not known the true horror of nuclear weapons. I believe we must seriously understand the horror."

After the lecture, one of the students said his account was more horrible than she had imagined. She also said she hopes people in other countries will learn more about atomic bombs and that she wants everyone to think of ways to achieve peace.

Saiki said he thinks he can give talks for four or five years, considering his age, and that he will prioritize this task.