“From the 12th to the 15th we were in a location with one of the highest levels of radiation,” said Tamotsu Baba, the mayor of Namie, which is about five miles from the nuclear plant. He and thousands from Namie now live in temporary housing in another town, Nihonmatsu. “We are extremely worried about internal exposure to radiation.”

The withholding of information, he said, was akin to “murder.”

In interviews and public statements, some current and former government officials have admitted that Japanese authorities engaged in a pattern of withholding damaging information and denying facts of the nuclear disaster — in order, some of them said, to limit the size of costly and disruptive evacuations in land-scarce Japan and to avoid public questioning of the politically powerful nuclear industry. As the nuclear plant continues to release radiation, some of which has slipped into the nation’s food supply, public anger is growing at what many here see as an official campaign to play down the scope of the accident and the potential health risks.

Seiki Soramoto, a lawmaker and former nuclear engineer to whom Prime Minister Naoto Kan turned for advice during the crisis, blamed the government for withholding forecasts from the computer system, known as the System for Prediction of Environmental Emergency Dose Information, or Speedi.

“In the end, it was the prime minister’s office that hid the Speedi data,” he said. “Because they didn’t have the knowledge to know what the data meant, and thus they did not know what to say to the public, they thought only of their own safety, and decided it was easier just not to announce it.”

In an interview, Goshi Hosono, the minister in charge of the nuclear crisis, dismissed accusations that political considerations had delayed the release of the early Speedi data. He said that they were not disclosed because they were incomplete and inaccurate, and that he was presented with the data for the first time only on March 23.