Fukushima caused 'mutant butterflies'

Genetic mutations have been found in three generations of butterflies from near Japan's crippled Fukushima nuclear plant, scientists said on Tuesday, raising fears radiation could affect other species.

Around 12 percent of pale grass blue butterflies that were exposed to nuclear fallout as larvae immediately after the tsunami-sparked disaster had abnormalities, including smaller wings and damaged eyes, researchers said.

The insects were mated in a laboratory well outside the fallout zone and 18 percent of their offspring displayed similar problems, said Joji Otaki, associate professor at Ryukyu University in Okinawa, southwestern Japan.