VIENNA (AFP) – The head of the UN's nuclear watchdog warned on Monday that confidence in atomic energy had been "deeply shaken" by the Fukushima disaster as a conference began to debate lessons to be drawn of the crisis in Japan.

"The eyes of the world will be upon us in the next few days," Yukiya Amano said at the start of the five-day ministerial meeting of the International Atomic Energy Agency (IAEA) in Vienna.

"Public confidence in the safety of nuclear power has been deeply shaken."

Since the disaster at Japan's Fukushima nuclear plant in the wake of the March 11 earthquake and tsunami, several countries, such as Germany, Italy and Switzerland, have decided to abandon nuclear power.

Still, Amano noted: "Nuclear power will remain important for many countries."

"Nuclear events respect no borders so an international approach to nuclear safety is essential," he added.

"Business as usual is not the option."

States with nuclear power should accept a combination of domestic and international measures to ensure more credible, transparent and efficient monitoring of their nuclear power plants, Amano suggested.

"National assessments are the starting points, but they should be followed by IAEA international expert peer reviews," he insisted, pushing further for "systematic, periodic peer reviews by the IAEA".

"IAEA review of every one of the world?s 440 operating nuclear reactors in just a few years is not a realistic proposition," he admitted, but suggested instead a "system based on random selection".

"The Agency could conduct an international safety review of one nuclear power plant in 10 throughout the world over, say, a three-year period," he went on.

Amano also proposed strengthening the IAEA's existing safety criteria and making sure it was applied in every country.

In a report to be handed to the agency's 151 member states, the IAEA criticised Japan's response after the Fukushima accident, especially its failure to implement the agency's convention on dealing with nuclear emergencies.

The convention lays down the rules for cooperation between the nuclear watchdog and states that may need help, in the areas of security and communication.

The IAEA report was drawn up based on an experts' visit to Japan last month.

A preliminary version of the document, presented in Tokyo earlier this month, said Japan had underestimated the hazard posed by tsunamis to nuclear plants, but praised Tokyo's response to the March 11 disaster as "exemplary".