TOKYO -- A Japanese survivor of the U.S. atomic bombing of Hiroshima who was hugged by President Barack Obama during a recent visit to the city said Friday he still trusts the president's promise to work toward a nuclear-free world.

Shigeaki Mori, 79, told reporters that Obama's speech last month in Hiroshima convinced him that it wasn't an empty promise.

"I thought he really meant it," Mori said, recalling his emotional encounter with Obama. "I thought he really cares about world peace and strives to achieve it in his lifetime, and was not just saying it to be nice."

He said he listened carefully to Obama's speech in Hiroshima on May 27, and to his earlier speeches including one in The Hague which helped him win the Nobel Peace Prize, and thought Obama is a man of principle and is serious about achieving a world without nuclear weapons.

Obama's visit to Hiroshima was the first by a serving U.S. president. He offered flowers and called for a nuclear-free world, but did not apologize for the bombing.

Obama's speech generally won praise in Japan, but a survivors' group, Nihon Hidankyo, criticized him for not acknowledging any direct U.S. responsibility. It said an expression Obama used at the beginning of his speech, "death fell from the sky," sounded as if the bombing had been a natural disaster. The group said Obama had backpedaled from his speech at The Hague and urged him to take concrete steps toward nuclear disarmament.

The U.S. atomic bombings of Hiroshima and Nagasaki in the final days of World War II devastated both cities and killed more than 200,000 people.

Mori survived the Aug. 6, 1945, bombing in Hiroshima at age 8, miraculously without any injuries although he was within 2.5 kilometres (1.5 miles) of ground zero.

As amateur historian, he has devoted more than half of his life to piecing together the fates of a dozen U.S. airmen who were held as prisoners of war in Hiroshima and were killed by the bomb.

He started his research after learning in the 1970s that one of the American POWs had been found dead near a school he was supposed to transfer to. He could have been the one who had died, he thought. He began tracking down the American POWs to find their relatives.

His decades-long lonely struggle paid off when Obama visited Hiroshima.

"Finally I was recognized for what I was doing, and they told me I was doing the right thing," he said. "The project hasn't earned me a penny but I've met wonderful people, and was recognized by the U.S. government. I couldn't be happier."