The planned restart of four reactors in central and southwestern Japan will be delayed as nuclear operators need time to confirm whether peripheral equipment used parts affected by Kobe Steel's data fabrication, the operators said Thursday.

The reactors affected are the Nos. 3 and 4 units at Kansai Electric Power Co.'s Oi plant in Fukui Prefecture and the Nos. 3 and 4 units at Kyushu Electric Power Co.'s Genkai plant in Saga Prefecture. All four reactors were originally set to go online early next year.

According to the Nuclear Regulation Authority, which received reports from utilities after the data fabrication came to light, Kobe Steel Ltd. products were used in the four reactors. But the utilities said at the time they were not products affected by the data fabrication.