LONDON - Environmental group Greenpeace said today the eventual death toll from the Chernobyl nuclear disaster could be far higher than official estimates, with up to 93,000 cancer deaths attributable to the accident.

Based on research by the National Academy of Sciences of Belarus, the report said that of the 2 billion people globally affected by the Chernobyl fallout, 270,000 would develop cancers as a result, of which 93,000 would prove fatal.

The Chernobyl Forum, a group of eight UN agencies, and governments of Ukraine, Belarus and Russia, has estimated an eventual death toll of only a few thousand as a result of the April 26, 1986 explosion at the power plant in the Ukrainian town of Chernobyl.

The blast sent a plume of radioactive dust across northern and western Europe and as far as the eastern United States.

Greenpeace anti-nuclear campaigner Ivan Blokov accused the International Atomic Energy Agency (IAEA), the UN nuclear watchdog, of "whitewashing the impacts of the most serious nuclear accident in human history".

In Vienna, an IAEA official rejected the accusation, saying it was responsible in the Forum only for an environmental impact study while the casualty figures were drawn up by the World Health Organisation (WHO).

Gregory Haertl, a spokesman for Geneva-based WHO, said it stood by its figures. He said the predicted eventual number of extra deaths in the hardest-hit areas of Ukraine, Belarus and Russia was estimated to be 4000.

Another 5000 deaths were predicted among those who had been living in less-contaminated zones of the three countries at the time of the disaster, he added.

Haertl also noted that WHO had not done a European-wide study and said Greenpeace's figures appeared to assume one.

The Greenpeace report said that a further 200,000 people in Russia, Ukraine and Belarus could have died as a result of medical conditions -- such as cardiovascular diseases -- attributable to the disaster, but that there was no accepted methodology to calculate deaths from such diseases.

The report said the incidence of cancer in Belarus had jumped 40 per cent between 1990 and 2000, with children not yet born at the time of the disaster showing an 88.5-fold increase in thyroid cancers.

Haertl questioned Greenpeace's estimated 10 per cent death rate for thyroid cancers among children and adolescents. "We actually know the death rate is one per cent. They are overstating the figures," he said.

Leukaemia is also reported to be on the increase in the Chernobyl region, as are cases of intestinal, rectal, breast, bladder, kidney and lung cancers, the Greenpeace report said.

The relocation of hundreds of thousands of people has put further strains on the population.

"The Chernobyl accident disrupted whole societies in Belarus, Ukraine and Russia," Greenpeace concluded.

"A complex interaction between factors such as poor health, increased costs of health systems, relocation of people, loss of agricultural territories, contamination of foodstuffs, economic crisis, the costs of remediation to the states, political problems, a weakened workforce ... creates a general crisis."