A government panel investigating the Fukushima nuclear crisis is expected to state in an upcoming report that the evacuation order issued shortly after the accident began was irrational, sources said.

The government ordered people living within 20 km of the plant to evacuate, but the panel believes the order led some residents to move to areas where radiation was actually higher and created mass confusion, the sources said.

The prime minister's office received its first fallout estimate on March 23 — or 11 days after the first hydrogen explosion occurred at the Fukushima complex. The estimate was based on data from the government's special computerized System for Prediction of Environmental Emergency Dose Information (SPEEDI).