The radiation doses workers received in the initial phase of the Fukushima disaster may have underestimated by 20 percent, a report by a U.N. panel says.

The U.N. Scientific Committee on the Effects of Atomic Radiation said in a summary report on its website that the Japanese government and Tokyo Electric Power Co., known as Tepco, used tests that failed to take into account some types of radiation released by the three meltdowns at the Fukushima No. 1 power plant in March 2011.

The report said the committee analyzed the doses received by some 25,000 people working at the plant on or before October 2012, using data from Japan, Tepco and others to assess the amount of substances discharged during the crisis after the March 2011 earthquake and tsunami.