ATLANTA (AP) — The top U.S. Nuclear Regulatory Commission official in Japan says his team warned higher-ups that water could be seeping from a spent fuel pool at the Fukushima Dai-ichi nuclear plant.

Charles Casto oversees the NRC's response to a nuclear crisis caused by an earthquake and tsunami on March 11.

The condition of the spent fuel pool became a political controversy. Early on, NRC Chairman Gregory Jaczko told lawmakers that one pool holding hot, radioactive nuclear fuel was dry, a development that would have significantly worsened the crisis. Japanese officials denied it. The NRC later acknowledged that may have been wrong.

Casto said his team's warning was based on the best available circumstantial evidence. He said the warning was not "unreasonable" considering the damage at the stricken plant and other information.

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