This was 20 years after the accident but we heard of many unusual clusters of people with rare bone cancers. One doctor, in tears, told us that one in three pregnancies in some places was malformed and that she was overwhelmed by people with immune and endocrine system disorders. Others said they still saw caesium and strontium in the breast milk of mothers living far from the areas thought to be most affected, and significant radiation still in the food chain. The doctors and scientists who have dealt directly with the catastrophe said that the UN International Atomic Energy Agency's ''official'' toll, through its Chernobyl Forum, of 50 dead and perhaps 4000 eventual fatalities was insulting and grossly simplistic. The Ukrainian Scientific Centre for Radiation, which estimated that infant mortality increased 20 to 30 per cent after the accident, said its data had not been accepted by the UN because it had not been published in a leading scientific journal.

Konstantin Tatuyan, one of the ''liquidators'' who helped clean up the plant, told us that nearly all his colleagues had died or had cancers of one sort or another, but that no one had ever asked him for evidence. There was burning resentment at the way the UN, the industry and ill-informed pundits had played down the catastrophe.

While there have been thousands of east European studies into the health effects of radiation from Chernobyl, only a very few have been accepted by the UN, and there have been just a handful of international studies trying to gauge an overall figure. They range from the UN's Scientific Committee on the Effects of Atomic Radiation study (57 direct deaths and 4000 cancers expected) to the International Physicians for the Prevention of Nuclear War, which estimated that more than 10,000 people had been affected by thyroid cancer alone and a further 50,000 cases could be expected.

Moving up the scale, a 2006 report for Green members of the European Parliament suggested up to 60,000 possible deaths; Greenpeace took the evidence of 52 scientists and estimated the deaths and illnesses to be 93,000 terminal cancers already and perhaps 140,000 more in time. Using other data, the Russian Academy of Medical Sciences declared in 2006 that 212,000 people had died as a direct consequence of Chernobyl.

Fukushima is not Chernobyl, but it is potentially worse. It is a multiple-reactor catastrophe happening close to a metropolis of 30 million people. If it happened at Sellafield, there would be panic in every major city in Britain. We still don't know the final outcome, but to hear experts claiming that nuclear radiation is not that serious, or that this accident proves the need for nuclear power, is nothing short of disgraceful.