Japanese automaker Daihatsu Motor suspended operations at its main assembly plant in Osaka on Tuesday. This comes after irregularities were found in safety test data.

Production has now come to a halt at all four of the carmakers' factories in Japan. The plants in Shiga, Kyoto and Oita prefectures were shut down on Monday.

Daihatsu made the move after 174 additional data irregularities were found in tests involving 64 models. The cars were being tested for government certification.

The carmaker said it does not know when the factories will reopen. It added that workers will be engaged in cleaning and maintenance duties until the end of January.
An employee who arrived to work at the main plant on Tuesday said he is wondering when operations will resume and is worried about his livelihood.

The unusual situation is likely to affect regional economies across Japan, the company's business partners and subcontractors.

Daihatsu has apologized for causing a lot of trouble and inconvenience. It says it will respond carefully to the concerns of clients.