TOKYO - Masakazu Toyoda, Chairman and CEO of the Institute of Energy Economics of Japan, said reflecting on the accident at the Fukushima Daiichi Nuclear Power Plant, it was essential that the nuclear power watchdog performed its role effectively.

The nuclear accident triggered by the March 11 disasters last year was the worst in history after the 1986 Chernobyl one. The plant has been leaking radioactive substance into the environment, impacting people living around it.

In a written interview with Xinhua ahead of the two-day Nuclear Security Summit in Seoul which will begin on Monday, Toyoda said the accident exposed the management weakness in the nuclear power operators as well as the nuclear watchdog.

"They both were not well prepared for major accidents," Toyoda said, adding that ?nuclear power experts also failed to play a role when the top politicians were making decisions.

"Japan is focused on handling the aftermath of the accident and the prevention of radioactive substance, but the government also needs to consider how to take next step when all the prepared measures are in vain," Toyoda said,

He stressed that the operators must work very hard to ensure the security of the nuclear power plant. In the meantime, the nuclear power watchdog should also play its role effectively.

Toyoda suggested that the watchdog must be independent, not only of the nuclear power operators, but also of political situation.

"Regarding anti-terrorism, the impact of a nuclear accident may well go beyond borders, so there must be a multinational mechanism in case of emergency,"Toyoda said.

Leaders from over 50 nations and international organizations including Chinese President Hu Jintao and U.S. President Barack Obama are expected to review achievements scored since the Washington summit in 2010 at the Seoul event.

A Japanese delegate to the summit Miyagawa Makio, Director- General of the Foreign Ministry's Disarmament, Non-proliferation and Science Department told Xinhua Friday that Japan planned to release the country's new set of measures for ensuring the security of nuclear power in late March or early April.