The health effects of the Chernobyl nuclear disaster in Ukraine 20 years ago have been grossly under-estimated, says an environmental charity.
Kiev's Chernobyl museum shows photos of dead emergency workers
Official UN figures predicted up to 9,000 Chernobyl-related cancer deaths.
But Greenpeace says in a report released on Tuesday that recent studies estimate that the actual number of such deaths will be 93,000.
Stressing that there is a problem with diagnosis, it adds that other illnesses could take the toll to 200,000.
"Our problem is that there is no accepted methodology to calculate the numbers of people who might have died from such diseases," Greenpeace campaigner Jan van de Putte told Reuters news agency.
"The only methodology that is accepted is for calculating fatal cancers."
The explosion and fire at the Chernobyl nuclear plant in April 1986 was the world's worst nuclear accident.
It spread a cloud of radioactive particles across a huge swathe of Europe.
Several million people still live in contaminated areas.
The UN figure - of between 4,000 and 9,000 extra cancer deaths - came from a report released last October by the UN-led Chernobyl Forum.
In the report, the World Health Organization dramatically lowered the estimated Chernobyl death toll, suggesting confusion had been caused over the accident's impact.
HOW MANY DIED?
Acute Radiation Sickness (ARS) deaths in 1986: 28
ARS patients who died later: 19 (some from other causes)
Others who died during explosion: 2
Child thyroid cancer deaths (1992-2002): 15 (UN figure)
Predicted extra cancer deaths: from 4,000 (UN) to 93,000 (Greenpeace)
Estimated deaths from non-cancer causes 1990-2004: 107,000 (Greenpeace)
Dozens killed in accidents building sarcophagus (according to an engineer)
Many emergency and recovery workers, the report suggested, had died since 1986 from natural causes which could not be attributed to radiation exposure.
But in its report, Greenpeace suggests there will be 270,000 cases of cancer alone attributable to Chernobyl fallout, and that 93,000 of these will probably be fatal.
Blake Lee-Harwood, campaigns director at Greenpeace, told the BBC that cancer was likely to be the cause of less than half of the final fatalities.
"We're also looking at intestinal problems, heart and circulation problems, respiratory problems, endocrine problems, and particularly effects on the immune system," he told the BBC's World Today programme.
Mr Lee-Harwood cited technical reasons for the discrepancy.
However, he also alleged that the nuclear industry had a "vested interest in playing down Chernobyl because it's an embarrassment to them".
Doctor Oxana Lozova, who works at a children's hospital in Rivne district, 300km (190 miles) west of Chernobyl, said many generations appeared to be affected.
"I think the fallout from Chernobyl has affected the immunity of those who were young children at the time of the disaster," she told the BBC's Moscow correspondent, Damian Grammaticas.
"We now have to deal with people who are a lot weaker than their fathers and grandfathers were.
"They're falling ill at an age when they really should still be quite fit."
'Apples and oranges'
The WHO said comparing the Chernobyl Forum and Greenpeace reports was like "comparing apples and oranges" when it spoke to the BBC News website.
"The Greenpeace report is looking at all of Europe, whereas our report looks at only the most affected areas of the three most affected countries," said WHO spokesman Gregory Hartl.
"The WHO felt it had recourse to the best national and international scientific evidence and studies when it came up with its estimates of [up to] 9,000 excess deaths for the most affected areas. We feel they're very sound."
Mr Hartl rejected accusations of bias toward the nuclear industry in the report.
"We acting as [neither] an apologist nor an attacker of the nuclear industry," he said.
The original report found more than 600,000 people received high levels of exposure, including reactor staff, emergency and recovery personnel and residents of the nearby areas.