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Japan's nuclear watchdog has endorsed a panel's conclusion that a seismic fault running underneath an atomic plant in western Japan is active, making the plant's restart virtually impossible.

The Nuclear Regulation Authority said Wednesday that it agrees with experts that the fault underneath the Tsuruga No. 2 reactor poses a high risk if a major earthquake hits.

Japan prohibits reactors from sitting above active faults. Tsuruga's No. 2 reactor faces scrapping unless its operator provides new data overriding the decision.

The case is a crucial test for the watchdog to prove whether it can resist industry pressure just as Japan's pro-nuclear government moves to restart reactors suspended since the tsunami-caused 2011 Fukushima disaster.

Tsuruga's operator, the Japan Atomic Power Co., has rejected the decision and will continue its own probe.