Nippon Steel said on Monday it expected to restore 90% of output at its fire-damaged Nagoya plant by the end of September and its customers were unlikely to suffer any major disruption, according to Reuters.

The news agency said the nation's largest steel maker halted operations at its Nagoya plant - a main supplier of steel to Toyota, Honda and Mitsubishi - after a gas tank explosion and fire on Wednesday evening that injured 15 workers.

According to Reuters, vehicle makers had worried that any prolonged delay in restarting the plant, Nippon Steel's third-biggest, could damage business, but the steel maker said it did not see a serious situation developing.

"I think it is very unlikely that lost output will pose a disruption in production schedules for our customers," president Akio Mimura reportedly told a news conference, adding: "We are using every method available to see that doesn't happen."

According to Reuters, Nippon Steel said one of its two blast furnaces and its hot-rolling mill - through which steel sheets for cars pass - were working again and the second blast furnace is expected to be operational by mid-September though the plant would not be fully operational until next year.

Reuters said Nippon Steel has used other plants to deliver back-up supplies and rival JFE Holdings, Japan's second-largest steel maker, has said it is prepared to help with personnel, materials or supply to customers.

Reuters noted that the shutting of the plant has begun to disrupt some production schedules at Toyota, which declined to say how many vehicles a cancellation of overtime, except for the new Prius, would translate into, but business daily the Nihon Keizai put it at around 1,000 to 1,400 vehicles or as much as 10% of production.

Toyota told Reuters its plants would run without overtime again on Tuesday, with a decision on overtime assembly for the Prius to be decided that afternoon while the schedule for Wednesday and beyond will be decided later on Monday.

Honda and Mitsubishi Motors told the news agency their factories will run on schedule until Friday.

"We have the supplies needed to run our plants on schedule until September 12, beyond that, it will depend on Nippon Steel," a Honda spokesman told Reuters.