The United States dropped an atomic bomb on Hiroshima on August 6, 1945, killing some 140,000 people. Three days later a second device was used on Nagasaki, with some 74,000 others losing their lives.

Representatives from 120 countries and regions -- plus the European Union -- are expected to attend the Hiroshima ceremony on Wednesday, according to Hiroshima officials.

These however don't include prominent nuclear states like Russia, China and Pakistan.

Hiroshima this year didn't handpick and "invite" foreign representatives, instead "notifying" all countries and regions that the event will be held.

This allowed the city to approach economies Japan doesn't officially recognise as countries, such as Taiwan and Palestine, both of which are expected to attend for the first time.

Meanwhile, Nagasaki said Friday that its memorial is also expected to draw a record turnout.

As of Monday last week, 101 countries and regions had provisionally expressed their intentions to attend.

This includes Russia, attending for the first time since its invasion of Ukraine in 2022.

Nagasaki's decision last year to exclude Israel's ambassador prompted the then US envoy to Japan to boycott the ceremony.

The city said at the time that the move was "not politically motivated" but a safety precaution against potential disturbances like protests over the Gaza conflict.

"We wanted attendees to visit us and know first-hand the reality of what catastrophe a nuclear weapon can bring", a Nagasaki official told AFP last week.

Japan announced its surrender in World War II on August 15, 1945.