Mazda Motor has apologized to shareholders for its involvement in a recent testing and certification scandal. The Japanese automaker admitted to cheating on a series of engine and safety tests.

President Moro Masahiro assured shareholders that the wrongdoing won't happen again.

Earlier this month the firm admitted to rigging the results of engine output tests for two models.

It also said it didn't perform proper crash tests for three others that are no longer in production.

In a separate case, Nissan Motor was also trying to placate shareholders on Tuesday.

President and CEO Uchida Makoto reportedly expressed regret for the firm's treatment of subcontractors.

In March Nissan received an advisory from the Fair Trade Commission for unfairly cutting prices to be paid to 36 suppliers. The commission said the action was in violation of the law.

Nissan plans to explain to the commission how it will ensure the practice doesn't happen again.