Tokyo – Mitsubishi Motors said Wednesday that its years-long cheating on fuel-economy tests did not affect cars sold overseas, potentially limiting the scope of a scandal that has plunged the automaker into crisis.

The company also said it was probing nine more models sold only in Japan, but ruled out a bailout from its top shareholders.

Vehicles sold overseas “were tested using methods appropriate to those markets”, Mitsubishi chairman Osamu Masuko told reporters.

“We believe the vehicles sold overseas are not affected.” The company was still investigating why cars sold in Japan were caught up in the scandal, he added.

However, it said “overly optimistic” fuel-economy targets could be to blame for some employees fudging the tests.

In some cases, cars appeared to be about 15 per cent more fuel-efficient than they were in reality.

Mitsubishi is reeling after it admitted last month to the improper testing, and that unnamed staff manipulated data.

Despite fears about Mitsubishi’s future, executives ruled out a bailout.

“As far as assistance is concerned, there have not been any concrete talks,” Masuko said Wednesday, as the firm submitted a report on its internal investigation to the transport ministry.

“Our company’s finances are relatively healthy. At this point, we think we can do this on our own.”

Mitsubishi was pulled from the brink of bankruptcy a decade ago after it was discovered that it covered up vehicle defects that caused fatal accidents.

The vast Mitsubishi group of companies stepped in with a series of bailouts, saving the embattled firm.

But it is not clear if they would be so willing to help this time around as the automaker faces possibly huge fines, lawsuits and customer compensation costs.

Earlier Wednesday, Japan’s Asahi newspaper said the under-fire company had cheated on tests for almost every model it sold in its home market over the past 25 years.

Citing unnamed company sources, the report said dozens of models sold in Japan have been affected since 1991, including sedans and sports utility vehicles (SUVs) such as the popular Pajero model.

So far, Mitsubishi has confirmed that four models and over 600,000 vehicles – all sold in Japan – were involved in the cheating scandal, but warned the number of cars affected would likely rise.

On Wednesday, it said it was probing nine more existing models for misstating their fuel efficiency, as well as those no longer in production.

Mitsubishi sold about one million vehicles globally last year.

The company has said it could not make financial forecasts for the current fiscal year in light of the potential damage from the scandal, including the possibility of big fines, lawsuits and compensation costs.