Barack Obama's trip to Hiroshima this month is a chance for him to see how the city suffered after its atomic bombing, and to renew his push for global nuclear disarmament, local officials said Wednesday.

On May 27, Obama will become the first sitting US president to visit Hiroshima, the White House said Tuesday, stressing there would be no apology for the city's devastation in the final days of World War II.

Obama, who will be in Japan for a Group of Seven summit, will make the pilgrimage to Hiroshima's Peace Memorial Park accompanied by Japanese Prime Minister Shinzo Abe.

"I hope that here in Hiroshima he will conceive concrete steps towards a nuclear-free world," said city mayor Kazumi Matsui.

About 140,000 people died after US forces dropped an atomic bomb on Hiroshima on August 6, 1945.

Tens of thousands were killed by the fireball that the powerful blast generated, with many more succumbing to injuries or illnesses caused by radiation in the weeks, months and years afterwards.

Vast swathes of the city, including many of its military and industrial installations, were flattened.

The southern city of Nagasaki was hit by a second bomb days later, killing 74,000 people, in one of the final acts of World War II.

Hidehiko Yuzaki, the governor of Hiroshima prefecture, told reporters he hoped Obama would see "the reality of how the atomic bomb hurt people here, and would come away with a deep understanding of the scale of the damage."

Although many survivors of the attack may hope for an apology, Yuzaki said the key issue was simply that humanity "should never ever suffer such an experience again."

Hiroshima is now a thriving, modern city, little different from many others in Japan, although the bombed-out remains of a domed building stands tribute to those who died in the world's first ever atomic attack.

Last month US Secretary of State John Kerry laid a wreath near the building, and visited the "gut-wrenching" memorial museum that shows the human cost of the bombing.

Japan has long urged world leaders to visit Hiroshima and Nagasaki to see the horrors of the atomic bombings and join efforts to eradicate nuclear arms.

Former president Jimmy Carter visited Hiroshima after leaving office, while Richard Nixon went to the city a few years before assuming the presidency.