The United Nations report, which found that only 56 people had so far died and 4000 could eventually perish from the effects of the disaster, was being discussed at a two-day conference in Vienna sponsored by the International Atomic Energy Agency (IAEA).
"Their goal is to push for development of nuclear energy," said Oleksiy Pasyuk, of the environmental group Ukraine National Ecology Centre on Tuesday.
"They want to lower distrust of nuclear energy."
"We are worried that they are suggesting allowing people to once again live in the affected areas," Pasyuk told AFP.
The report said that, aside from a 30km zone immediately surrounding the reactor that exploded in 1986 and several closed forests and bodies of water, radiation levels have normalised in many places that today are still widely considered dangerous.
Volodymyr Usatenko, who advises a parliamentary commission on nuclear safety, likewise dismissed many of the report's findings.
"The report is based on absolutely false figures," he said. "It is based on official data, on data from a government that never felt responsible."
The UN report, which was being discussed by nuclear, health and development experts in Vienna, concludes that out of more than 600,000 people who suffered the most exposure from the accident - reactor staff, emergency and recovery personnel in 1986-87 and residents of the nearby areas - an estimated 3940 are expected to die from radiation-induced cancer and leukaemia.
The Greenpeace environmental group also denounced the report, saying it was "whitewashing" the impact of the world's worst nuclear accident.
Greenpeace activits have
denounced the UN report
"It is appalling that the IAEA is whitewashing the impacts of the most serious industrial accident in human history," said Jan Van de Putte, a Greenpeace nuclear campaigner, in a statement released by the organisation's headquarters in Amsterdam.
"Denying the real implications is not only insulting the thousands of victims - who are told (they are) sick because of stress and irrational fears - but it also leads to dangerous recommendations, to relocating people in contaminated areas," Van de Putte said.
Greenpeace said a more careful reading of the 600-page report and other published research by UN bodies leads to a different conclusion.
The ecological group also cited omissions in the report.
It said that the 4000 deaths only relate to a studied population of 600,000, whereas radiation was spread over most Europe and the report omits the impact on millions of Europeans.
The World Health Organisation also referred to a study of 72,000 Russian workers at the nuclear plant, but Greenpeace said the number of workers in Russia, Belarus and Ukraine was estimated at nearly 10 times that figure.
"Chernobyl was, is and will be one of Ukraine's biggest problems," said Oleh Andreev, spokesman for Ukraine's Emergency Situations Ministry.
Belarus Petrov, 3, is among
cancer victims of the disaster
"The one who says the devil is not as black as he is painted had better live here and see the problem from the inside," said Andreev.
Head of the Chernobyl Union action group, Yuriy Andreev said "The medical and biological consequences are very heavy."
He cited increases in cancer of the blood, marrow, lung, liver and intestine.
"The situation with thyroid cancer is dramatic," said Galyna Terekhova, a doctor at the Kiev Institute of Endocrinology.
The UN report acknowledges that thyroid cancer has become more prominent but said the survival rate has been almost 99%. However, at least nine children have died of the disease.
Andreev, the Ukrainian activist, also warned that the international community had not yet fully grappled with the environmental effects of Chernobyl.
He said that most of the 800 depots in the 8km sanitary zone around the plant where radioactive fuel, contaminated clothes and vehicles are preserved do not meet safety requirements.
"The report is based on absolutely false figures. It is based on official data, on data from a government that never felt responsible"
Nuclear safety parliamentary commission advisor
"One of the depots that preserves thousands of tons of ... used fuel is not hermetic," said Andreev, warning about constant leaks into the subsoil waters then into the Prypiat River, a Dnipro tributary.
The Dnipro supplies Kiev residents with drinking water.
Chernobyl's number-four reactor, in what was then the Soviet Union and is now Ukraine, exploded on 26 April 1986, sending a radioactive cloud across Europe.
In an effort to prevent further radiation release, engineers hastily erected a shelter over the damaged reactor, but parts of it are crumbling and experts say it needs urgent repairs.