The total number of the explosion-affected people or "hibakusha" from the Second World War atomic bombing by the US is more than 15,000 people recorded in the previous file, according to research conducted by the city government.
Based on a fresh review of 120,000 documents which was undertaken by computer for the first time, the number of atomic bomb victims has grown by around 15,000 compared with the previous tally 14 years ago, the data showed, Kyodo News agency reported.
The remainder includes people who later entered areas near ground zero and those who lacked sufficient information about their whereabouts.
After eliminating duplications, the death toll from the bombing was lowered to 277,996, from the previously reported 280,959, the report said.
The study will most likely be the last one because 68 years have passed since the bombing and it is unlikely that any new documents will be discovered, an official suggested.