Daihatsu on Monday suspended operations at three domestic automobile assembly plants in the wake of its vehicle testing fraud scandal.

The move comes after the automaker was instructed by the transport ministry last week to stop shipments until its vehicles are confirmed to meet the government's safety and environmental standards.

It is unclear when the company will resume production, which is expected to be suspended until at least the end of next month.

The company's plant in the town of Ryuo, Shiga Prefecture, and its plant in the town of Oyamazaki, Kyoto Prefecture, as well as subsidiary Daihatsu Motor Kyushu's plant in the city of Nakatsu, Oita Prefecture, were the facilities where operations were suspended.

Daihatsu plans to take its head office plant in the city of Ikeda, Osaka Prefecture, offline on Tuesday, completing suspensions at all four vehicle assembly factories.

On Friday, the company halted Daihatsu Motor Kyushu's engine plant in the city of Kurume, Fukuoka Prefecture.

The automaker's labor union is demanding that the company pay 90% of regular wages to workers at the affected factories during the suspension period.

Despite the suspensions, Daihatsu will have many plant employees work through Thursday to clean up the factories. It is still considering the handling of workers after the turn of the year.

It is feared that the vehicle test scandal will deal a blow to local economies, with parts suppliers and other businesses, including dealerships, that had expected to see strong year-end sales affected by the production suspensions.