TOKYO - Tokyo Electric Power Company Holdings Inc. told nuclear regulators on Monday that it will push back the planned commercial operation of the first reactor it has brought back online after the 2011 Fukushima nuclear disaster, following signs of an electricity leak.

The Kashiwazaki-Kariwa nuclear power plant's No. 6 reactor in Niigata Prefecture, which resumed operation on Jan. 21, was slated to begin commercial operation on Wednesday.

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