Experts investigating Japan's nuclear disaster said on Monday that the operator of the crippled plant continues to drag its feet in investigations and has tried to understate the true amount of damage at the complex.

The report, by a government-appointed panel, is the latest of several to fault Tokyo Electric Power Co and the government for doing too little to protect the Fukushima Daiichi plant from the massive earthquake and tsunami that set off three meltdowns there in the world's worst nuclear accident since Chernobyl.

The panel, of 10 independent experts in fields including radiation protection, medicine and law, also said the utility has yet to address problems within its own culture that contributed to its failings in the crisis - including employees "not fully trained to think for themselves".

"We still don't perceive much enthusiasm in the accident investigation from" the company, the report said. "TEPCO must take our findings sincerely and resolve the problems to achieve a higher level of safety culture across the company."

The panel said TEPCO covered up unfavorable data in a computer analysis attempting to measure the extent of damage inside the reactors earlier this year. It said that in a hearing, TEPCO officials acknowledged the simulation was inadequate, but they have yet to make another attempt. "The fundamental problem lies in the fact that utilities, including TEPCO and the government, have failed to see the danger as reality as they were bound by a myth of nuclear safety and the notion that severe accidents do not happen at nuclear plants in our country," it said.

The 450-page report is the fourth inquiry into the worst nuclear accident in a generation which occurred after the huge tsunami of March 2011 crashed into the Fukushima Daiichi nuclear power station.

Reactors went into meltdown, sending clouds of radiation over a wide area, forcing tens of thousands of people from their homes, some possibly for the rest of their lives.

A damning parliamentary study that said the disaster was "man-made" was released earlier this month, following a private report by a group of journalists and scholars.

An investigation by TEPCO largely cleared itself of blame, saying the size of the earthquake and tsunami was beyond all expectations and could not reasonably have been foreseen.

The latest report said however that TEPCO and the Nuclear and Industrial Safety Agency were ill-prepared to cope with a tsunami or severe accidents, and that the government bungled the evacuation.

AP-AFP