The Japanese government has appealed a recent court ruling awarding state healthcare benefits to people exposed to radioactive "black rain" which fell immediately after the 1945 atomic bombing of Hiroshima outside of a currently designated zone, Japan's Health, Labor and Welfare Minister Katsunobu Kato said Wednesday.

"This cannot be said to be a judgment based on sufficient scientific knowledge," said Kato on the grounds of appeal. 

But he also said at a news conference that the central government plans to review the area covered by its healthcare program. "We will examine it with a sense of speed, eyeing the possibility of expanding the area" in consideration of aging atomic bomb survivors, he said.

In late July, the district court ruled the 84 plaintiffs in their 70s to 90s, including the deceased, who were outside the area protected by the Japanese government, were all victims of the nuclear explosion. They hoped to receive the same health benefits as provided to atomic bomb survivors living in the zone where the state has recognized black rain fell.

It was the first court decision concerning the boundary of the target area.

The Hiroshima prefectural and city governments were in the position of the defendants because they were responsible for issuing health manuals for victims of nuclear explosions, together with the state. But previously, they also asked the central government, which designed the healthcare aid policy, to expand the scope of the target area.

The local governments accepted the state's decision to appeal the ruling to review the boundaries of the zone in consideration of the central government's attitude towards verification of target areas. 

Wednesday was the deadline for an appeal.

(With input from agencies)