Japanese Prime Minister Yoshihiko Noda urged world leaders not to be lulled into a "myth of safety" regarding nuclear power.

Speaking Tuesday at the Nuclear Security Summit in Seoul, Noda shared Japan's lessons learned from the Fukushima nuclear power plant, which was knocked out by last year's earthquake and tsunami, resulting in the worst nuclear crisis since the 1986 Chernobyl disaster in Ukraine.

In response to the Fukushima disaster, he said, the Japanese government will "fundamentally strengthen domestic nuclear security measures," giving the still-to be-established Nuclear Regulatory Agency a central role.

Admitting that training for on-site workers at Fukushima had been "insufficient," Noda said that Japan would strengthen response procedures and inter-agency coordination manuals.

He said Japan will also conduct "rigorous" training and joint field drills involving the police and the Japanese land military, as well as between the Japan coast guard and the Japanese maritime force.

Noting that the total loss of power at Fukushima hadn't been adequately anticipated, the prime minister said Japan will enhance power supplies and reinforce vulnerabilities in the power supply system.

Such measures, he said -- without indicating exactly what steps would be taken - would also help to prepare against a potential terrorist attack on a nuclear power plant.

Failure to anticipate an accident as severe as Fukushima stemmed from "naive anticipations," Noda admitted, underscoring the need for "a thoroughly prepared contingency plan based on the premise of preparing for the unanticipated risks."

But, he warned, "a man-caused act of sabotage will test our imaginations far more than any natural disaster."

"We must make use of the knowledge and lessons gained from the (Fukushima crisis) to prepare for 'human-induced harm' such as terrorist attacks on nuclear power plants," Noda said.

Among the measures to beef up security against terrorist attacks on Japan's nuclear power plants, he said the government will increase the number of armed police and Japan coast guard and strengthen patrols.

Japan is also considering conducting thorough identity checks on nuclear plant workers.

And to protect against cyberattacks, the government "has strengthened measures to block the computer systems of nuclear facilities from outside networks," he said.

He urged countries to closely cooperate and combine their expertise, so as not to take lightly natural disasters or to lose the "battle of wits" against terrorists.

He said that at the end of this year Japan, along with the International Atomic Energy Agency, will host a conference in Fukushima on world nuclear safety.

Noda's remarks came a day after Tokyo Electric Power, the operator of the Fukushima plant, shut down the No. 6 reactor at its seven-unit Kashiwazaki-Kariwa complex in Niigata prefecture for stress tests, leaving all but one of Japan's 54 commercial nuclear power plants in operation. The last one, Hokkaido Electric's Tomari, is to go offline May 5 for maintenance.