Chief Cabinet Secretary Yoshimasa Hayashi has described the impact of recent “fraudulent activity” in the Japanese auto industry as likely “minimal,” adding that the government will take measures to minimize economic damage caused by data falsification disclosed Monday by five companies.

His comments at a news conference on Thursday came as Toyota and Mazda halted production of a total of four models in response to the discovery of shortfalls in their auto-testing procedures.

Toyota temporarily stopped manufacturing its Corolla Fielder and Corolla Axio models at Toyota Motor East Japan plants in Miyagi and Iwate prefectures. The company expects the hiatus to last until June 28.

The Yaris Cross will remain in production for export but not for domestic sales, it said.

Workers affected by the suspensions will be shifted to the production of other vehicles.

Mazda said that it halted production of two models — the 1.5-liter Mazda 2 and 1.5-liter Roadster RF. They are manufactured at its Yamaguchi and Hiroshima plants.

The company could not confirm the length of the stoppage. It said it will decide based on advice from the transport ministry.

Mazda workers affected by the production suspensions will likely be scheduled for training, although a plan has not been confirmed, it said.

On Monday, in a dramatic series of news conferences and formal announcements, five Japanese companies admitted to the falsification of testing data or the improper testing of vehicles.

Honda, Yamaha and Suzuki also disclosed failures in their certification procedures, in addition to Toyota and Mazda.

They admitted to falsifications including the rewriting of engine-control software and the improper modification of test vehicles in crash tests.

A total of 38 models were covered in the announcements.

Shipments of some vehicles were stopped when certification deficiencies were first disclosed. Now, production has been temporarily suspended for four of those models.

On Tuesday, five government inspectors began reviewing materials and conducting interviews at Toyota’s headquarters in Aichi Prefecture.

Toyota has emphasized that its cars are safe and have been adequately tested despite the compliance failures, and has noted that no vehicles have been recalled due to the recent questions about certification.

Auto company executives and industry consultants have raised questions about the Japanese auto industry's certification process, suggesting that the testing requirements may not be reasonable or appropriate and that failures in meeting the standards might not be material.

At Thursday's news conference, Hayashi said that the Ministry of Land, Infrastructure, Transport and Tourism will investigate data falsification by the vehicle makers and endeavor to contain the cost of their wrongdoings.

“We would also like to take measures in cooperation with the relevant ministries and agencies from the viewpoint of minimizing the impact on the economy.”

He was sanguine about the economic consequences of the falsifications.

“The fraudulent activity revealed this time, as far as it has been confirmed, is minimal in terms of the number of affected car models and the production volume compared to the fraud case of Daihatsu Motor,” Hayashi said, referring to an earlier incident in which the company — a Toyota group automaker — faked tests for decades.

Toyota shares rose about 1.7% in trading in Tokyo on Thursday, while Mazda shares declined about 0.9%.