NAGOYA -- Toyota Motor on Tuesday halted operations at all of its plants in Japan after a major supplier was hit by a cyberattack, disrupting the automaker's parts supply management system.
The company is suspending 28 lines at 14 plants. Subsidiaries Hino Motors and Daihatsu Motor will also halt operations at some plants in Japan on Tuesday.
The announcement that operations would be halted came on Monday, confirming an earlier Nikkei report.
Toyota later announced that operations across Japan will resume on Wednesday.
"We apologize to our relevant suppliers and customers for any inconvenience this may cause," Toyota said.
The cyberattack hit Kojima Industries, which supplies plastic parts to Toyota. Kojima announced on Tuesday morning that it has received a message demanding ransom and that it has confirmed the existence of a virus.
On Monday, an official close to Kojima Industries told Nikkei: "It is true that we have been hit by some kind of cyberattack. We are still confirming the damage and we are hurrying to respond, with the top priority of resuming Toyota's production system as soon as possible."
The company said on Monday it was still investigating the origin of the cyberattack, the specific malware involved and the damage caused. "Toyota representatives and cybersecurity experts are at Kojima Industries to determine the cause and how to restore" the system, a source familiar with the situation said.
Many of the roughly 400 tier 1 suppliers that Toyota deals with directly are connected to the automaker's kanban just-in-time production control system, which allowed the problems at Kojima Industries to spill over to Toyota. The automaker halted production to prevent longer-term damage, and prioritized inspection and recovery of the system.
Hino will suspend all operations at its Koga facility, which manufactures large and midsize trucks for export and domestic sale, and its Hamura plant, which makes small trucks and handles production for Toyota. The automaker has yet to determine whether work will resume Wednesday.
The Toyota shutdown includes a Daihatsu plant in Kyoto Prefecture. The halt is expected to reduce output by a few hundred vehicles.
"We are aware of media reports" on the incident, Prime Minister Fumio Kishida told reporters Monday night. "The government is working to confirm the situation." Law enforcement is also looking into the matter.