* Ministers, energy execs meet to discuss fall-out
* Campaigners renew calls for France to exit nuclear
* Greenpeace - other Japan reactors in critical situation
(Adds minister, Areva adviser comments)
By James Regan and Laure Bretton
PARIS, March 12 (Reuters) - French green groups renewed a call on Saturday for France to end its dependence on nuclear power, saying a radiation leak at a Japanese atomic power plant showed there were no safety guarantees in the industry.
The Japanese Daiichi 1 facility north of Tokyo started leaking radiation after an explosion blew the roof off the plant that had been shaken in a massive earthquake on Friday, raising fears of a meltdown. [ID:nL3E7EC09O]
French officials met to discuss the situation and possible precautionary measures, but green groups said it was time to dump a technology that had led to the worst civilian nuclear disaster in Chernobyl in 1986.
"It's clear that when there's a significant natural disaster, all the so-called safety measures fail in a country with the highest level of technical know-how," Cecile Duflot, head of the green Europe Ecologie-Les Verts party, told Reuters.
"Nuclear risk is not a risk that can really be controlled."
France has 58 nuclear reactors spread over 19 sites, providing almost four-fifths of the country's electricity and making it the second-biggest nuclear country after the United States. Japan has 55 nuclear reactors.
French anti-nuclear network "Sortir du nucleaire" described Japan's stricken nuclear plant as a "new Chernobyl".
"This is indeed a very serious nuclear accident ... of a severity comparable to that of Three Mile Island, and of Chernobyl which took place just about 25 years ago," the group said in a statement.
Chernobyl exploded in 1986, spewing out clouds of radioactivity. Human and technical error caused a confused response at Three Mile Island in Pennsylvania, leading to a meltdown of the core and a write-off of the reactor in 1979.
Japan's nuclear safety agency said it rated the incident as less serious than both accidents. [nTKZ00680] Nuclear experts said the Japanese reactor blast should not reach the magnitude of Chernobyl because the reactor's core seemed to be intact. [nLDE72B0AY]
Greenpeace said the situation was increasingly alarming.
"An explosion in one reactor could already have released very high doses of radioactivity, and other reactors also seem to be in a critical situation," Greenpeace said in a statement.
France's ASN nuclear safety authority said it was stepping up the monitoring of air quality over France.
The president of the IRSN radiation protection and nuclear safety institution, Agnes Buzyn, said real-time air quality data would be made available to reassure the public.
Buzyn and ASN's president met Ecology Minister Nathalie Kosciusko-Morizet, Energy Minister Eric Besson, the head of nuclear reactor maker Areva CEPFi.PA, Anne Lauvergeon, and representatives of power giant EDF (EDF.PA) on Saturday.
Besson told a news conference after the meeting the incident in Japan was a "serious accident" but not a "nuclear catastrophe". France's nuclear power plants had been built taking account of flood and earthquake risks, he said.
Areva's scientific adviser, Bertrand Barre, said the next steps were to study how the accident happened and how it could have been avoided.
"A serious accident like that will have repercussions in all countries with nuclear," he told Reuters. "If there are clear lessons, we will apply them. We need to take time to work out the consequences and act."
Barre said new Third Generation reactors would have additional safety measures to prevent accidents and limit the effects of any incident, including thicker concrete walls, systems to cool the reactor and water reservoirs.
Extra measures have already been taken in southeast France, the only area where there is considered to be an earthquake risk, and to protect French reactors against flooding after an incident at a plant near Bordeaux in 1999, Barre added. "The risk is so small, it's almost impossible to number," he said. (Additional reporting by Matthias Blamont; editing by Tim Pearce)