Prime Minister Junichiro Koizumi slammed Tokyo Electric Power Co. on Friday for allegedly falsifying reports on problems discovered at its nuclear plants.

"A power firm should give its highest priority to ensuring the safety of nuclear plants," Koizumi told reporters. Tepco should fully investigate the matter and take appropriate action, he said.

Earlier in the day, industry minister Takeo Hiranuma urged Tepco to take responsibility if the allegations prove to be true.