Japanese car maker Mitsubishi Motors Corp. has acknowledged that it has been falsifying its fuel economy tests since 1991.

"For the domestic market, we have been using that method since 1991," Ryugo Nakao, Mitsubishi's vice president, said during a press conference in Tokyo on Tuesday. At the moment, the number of affected Mitsubishi units is unknown yet.

Like Us on Facebook

The automobile company's president Tetsuro Aikawa admitted that an investigation is ongoing, and more irregularities could be discovered. He also said he does not know what possible reasons might have pushed the employees to falsify the fuel economy tests to ensure better mileage figures.

"We don't know the whole picture and we are in the process of trying to determine that. I feel a great responsibility," he said.

Mitsubishi announced that it has already organized a three-member committee composed of external lawyers to separately investigate the issue for about three months. After that, it will formally create a report and will notify the public about the results in a "timely manner."

Meanwhile, the automobile company's executives apologized over the matter, saying "[Mitsubishi] expresses its most sincere apologies to all of our customers, shareholders and stakeholders for any convenience or concern caused by this occasion."

According to the International Business Times, Mitsubishi posted a nearly $4 billion loss and shares plunged to nearly 50 percent after the scandal was exposed last week. 

Japanese officials raided Mitsubishi's office last Thursday and asked the company to submit its full report over the issue.

The inaccurate test also affected 157,000 units of eK Wagon and eK space and 468,000 Dayz and Dayz Roox vehicles manufactured for Nissan Motor Co.

TagsMitsubishi, emission scandal, Tetsuro Aikawa, automobile industry