Radiation is preventing the retrieval of hundreds of bodies from inside the 20-km evacuation zone around the Fukushima No. 1 nuclear power plant, police sources said Thursday.

Based on initial reports after the March 11 catastrophe, the number of bodies is estimated at between a few hundred and 1,000, one of the sources said, adding that high radiation is now hampering full-scale searches.

That view was supported by the Sunday find of high radiation levels on a body found in Okuma, Fukushima Prefecture, 5 km from the plant.

The rescuers are now in a bind. Even if they retrieve the bodies, anyone who comes into contact with them risks being irradiated, too, whether they're in the evacuation zone or not.

And if the bodies are cremated, the smoke could spread radioactive materials as well, the sources said. Even burial poses a problem. When the bodies decompose, they might contaminate the soil with radioactive materials.

Authorities are considering decontaminating and inspecting the bodies where they are found, but the sources said cleansing the decomposing bodies could damage them further.