The Supreme Court on Monday rejected a suit filed by people who were in the vicinity of Nagasaki at the time of the 1945 U.S. atomic bombing and seeking official recognition as atomic bomb survivors.

While turning down recognition of the 387 people as victims, the top court found one plaintiff who died after the suit was lodged could have been exposed to radiation after entering areas affected by the attack and sent his case back to the Nagasaki District Court.

The plaintiffs, who claimed they were within 12 kilometers of ground zero at the time of the atomic bomb attack on Aug. 9, 1945, are not classified as survivors, or hibakusha in Japanese, because they were outside the oval-shaped, state-designated zone stretching around 7 km from east to west and around 12 km from north to south.

Instead, they are defined as individuals "who experienced the bombing," and are not therefore entitled to full compensation including medical assistance as hibakusha are. As of late November, 6,278 such individuals who experienced the bombing lived in Nagasaki Prefecture, according to the prefectural government.

The top court's First Petty Bench presided by Justice Katsuyuki Kizawa upheld a 2016 Fukuoka High Court ruling which said an earlier scientific finding that radiation-linked health problems basically occurred within a 5-km range from ground zero was appropriate.

"I'm so disappointed and dumbfounded by the top court decision," said Chiyoko Iwanaga, 81, who leads the plaintiffs. "Although we are getting old and exhausted, I will keep challenging. The truth can't be bent."

In the suit filed in 2007, the plaintiffs had requested the central, Nagasaki prefectural and city governments issue health cards that entitle them to full compensation including medical assistance under a law supporting atomic bomb victims.

They also insisted they developed acute symptoms such as hair loss after exposure to the blast and still suffer from diseases related to radiation. But the top court upheld a 2012 Nagasaki District Court ruling that concluded the symptoms did not match those stemming from radiation exposure.

Under the law to provide support to atomic bomb victims, people are legally recognized as hibakusha if they were in the state-designated zone at the time of the atomic bombing, entered the city within two weeks of the attack, or were otherwise exposed to radiation from the explosion.

All of the plaintiffs argued they fall into the third category, while the man who died during the lawsuit demanded his case be classified as the second.