Nippon Oil Corp. is reportedly planning to increase fuel oil prices by as much as 28 percent to a record level for buyers, including Tokyo Electric Power Co. and Oji Paper Co., because of rising crude oil costs.

According to a notice sent by Japan's top refiner, customers will pay the higher prices in the three months to September.

Nippon Oil has been setting the nation's benchmark fuel oil price since 1970. Japan's 12 refiners, including Idemitsu Kosan Co., will probably follow Nippon Oil's move and raise prices. Tepco, Japan's biggest consumer of low-sulfur fuel oil, will pay Nippon Oil a record ¥101,870 a kiloliter, 28.1 percent more than in the three months that ended in June, according to the notice.

Oji Paper, the biggest high-sulfur fuel oil user, will pay ¥93,200 a kiloliter, up 26.6 percent from the previous quarter.