The world cannot take a "business as usual" approach to nuclear power in the wake of the disaster in Japan, UN atomic watchdog chief Yukiya Amano said Monday.
Amano suggested however that not enough was learned from an earlier incident in Japan where another nuclear power plant was damaged in an earthquake smaller than the one that caused last month's disaster.
"Thinking retrospectively, the measures taken by the operators as a safety measure (were) not sufficient to prevent this accident," Amano told reporters on the sidelines of a meeting on the Convention on Nuclear Safety (CNS).
The CNS is a treaty -- currently with 72 signatory countries -- drawn up after the 1986 Chernobyl disaster to ensure the safety of the world's atomic reactors.
Amano said the crisis in Japan caused by the March 11 earthquake and tsunami "has enormous implications for nuclear power and confronts all of us with a major challenge."
"We cannot take a 'business as usual' approach," he said.
The ageing Fukushima Daiichi nuclear power plant, 250 kilometres (155 miles) northeast of Tokyo, was hit by a 14-metre (46-foot) tsunami on March 11, triggering the world's worst nuclear accident since Chernobyl.
It is not the first such incident in quake-prone Japan: in 2007, the Kashiwazaki-Kariwa nuclear power plant was also damaged in an earthquake.
"That earthquake was much smaller than this one. And this time, the earthquake was followed by a huge tsunami," Amano said.
"I believe there are certainly ways to avoid the repetition of such an accident and for that purpose we are now thinking collectively and that is why we are preparing a ministerial meeting to launch the process."
The International Atomic Energy Agency (IAEA) is to host the conference with its 151 member states from June 20 to 24 to discuss lessons to be learned from the Fukushima disaster.
Li Ganjie of China's National Nuclear Safety Administration agreed that the Fukushima incident "has left an impact on global nuclear power development and has become a major event in nuclear history."
It had triggered "heated discussion on whether we should develop nuclear power."
IAEA chief Amano said that while the immediate priority at Fukushima "is to overcome the crisis and stabilise the reactors ... we must also begin the process of reflection and evaluation."
"The worries of millions of people throughout the world about whether nuclear energy is safe must be taken seriously," he said.
The Vienna-based IAEA, set up in 1957, is responsible for drawing up international safety standards for nuclear power plants, even if it has no powers to legally enforce those standards.
It has already dispatched expert teams to help monitor radiation release from the damaged reactors and sent two reactor experts to the plant to get first-hand information.
Amano said "more needs to be done to strengthen the safety of nuclear power plants so that the risk of a future accident is significantly reduced."
Many countries are reviewing their plans to set up nuclear power programmes in the wake of the Fukushima disaster.
But Amano insisted that the basic drivers behind the interest in nuclear power -- which included rising global energy demand, concerns about climate change, volatile fossil fuel prices and energy security -- "have not changed as a result of Fukushima."
He said he was "confident that valuable lessons will be learned from the Fukushima Daiichi accident which will result in substantial improvements in nuclear operating safety, regulation and the overall safety culture."
Explore further: Home cheap home: Vietnam architect's quest for low-cost housing