A Japanese district court has awarded official certification as atom bomb survivors to three South Korean men who said they were forced to work at shipyards there during World War Two.

The Mainichi daily said this appeared to be the first ruling of its kind.

The men, now in their 90s, will be known as "hibakusha", due to being present in Nagasaki when the US dropped the bomb in 1945.

The ruling provides them with some free healthcare coverage.

The lawsuit alleged they were forced to work at Mitsubishi Heavy Industries' Nagasaki Shipyard & Machinery Works.

Nagasaki Municipal Government had originally turned down their applications citing "a lack of evidence."

But this has now been overturned.

"All of a sudden the sky turned red with a huge bang and the windowpanes all shattered," one of the men testified about his experiences on the day of the bombing.