The operator of the Fukushima nuclear power plant and its regulators all failed in their duty to adequately prepare for and respond promptly to a major emergency, contributing to the worst nuclear accident in a quarter century, according to a committee investigating the disaster.

Tokyo Electric Power, the operator of the Fukushima plant, and its regulators were so unprepared for a major nuclear emergency that they lacked even the basic safety measures to respond to a disaster of the scale that hit Fukushima Daiichi nuclear power plant in the wake of the March 11 tsunami, the committee states in an interim report of its findings.

Tepco’s off-site emergency response headquarters for example, was housed in a building that “was not designed to withstand elevated radiation levels, although it was intended for use in nuclear emergencies”, and did not even have air cleaning filters, it says.