A section of the Chernobyl nuclear power plant in Ukraine has collapsed under the weight of snow but there were no injuries or any increase in radiation from the reactor that exploded in 1986, the country's emergency agency said Wednesday.

"The preliminary reason for the collapse was too much snow on the roof," the agency said, adding that the radiation situation is "within the norm" and nobody was harmed by Tuesday's incident. The roof was constructed after the 1986 disaster but is not part of the sarcophagus structure covering the reactor, it said.