Austria ? Fewer than 60 deaths have been directly attributed to radiation released by the 1986 Chernobyl nuclear power plant accident, and the final toll could be thousands less than originally believed, the U.N. nuclear watchdog agency said Monday.

However, anxiety caused by fear of death and illness from radiation poisoning is causing serious mental health problems, and such worries “show no signs of diminishing and may even be spreading,” the International Atomic Energy Agency said, citing a report compiled by 100 scientists.

The death toll attributed to radiation could reach 4,000, said the report, compiled on behalf of the Chernobyl Forum, a group that includes the Vienna-based IAEA, seven other U.N. agencies and the governments of Ukraine – where Chernobyl is located – Belarus and Russia.

Ukraine said previously it had registered 4,400 deaths related to the accident, and early speculation following the radiation release predicted that tens of thousands would die.

But forum chairman Dr. Burton Bennett said Monday that previous death tolls were inflated, perhaps “to attract attention to the accident, to attract sympathy.”

A two-day meeting to discuss the report starts today.