The head of Tokyo Electric Power Co. apologized Tuesday over his predecessor's order to not use the term "core meltdown" to describe the situation at the Fukushima No. 1 nuclear plant in the early days of the March 2011 crisis.

"It is extremely regrettable. People are justified in thinking it as a coverup," Tepco President Naomi Hirose said at a news conference in Tokyo.

The remarks came after a report published last Thursday said that then-President Masataka Shimizu instructed a vice president, who was taking part in a news conference on March 14, 2011, not to use "core meltdown" to describe the states of the reactors.