Toyota Motor Corp said it will suspend domestic factory operations on Tuesday, losing around 13,000 cars of output, after a supplier of plastic parts and electronic components was hit by a suspected cyber attack.
No information was immediately available about who was behind the possible attack or the motive.
The attack comes just after Japan joined Western allies in clamping down on Russia after it invaded Ukraine, although it was not clear if the attack was at all related.
Japanese Prime Minister Fumio Kishida said his government would investigate the incident and whether Russia was involved.
"It is difficult to say whether this has anything to do with Russia before making thorough checks," he told reporters.
Kishida on Sunday announced that Japan would join the United States and other countries in blocking some Russian banks from accessing the SWIFT international payment system. He also said Japan would give Ukraine $100 million in emergency aid.
A spokesperson at the supplier, Kojima Industries Corp, said it appeared to have been the victim of some kind of cyber attack.
A spokesperson from Toyota described it as a "supplier system failure."
The company does not yet know if the halt at its 14 plants in Japan, which account for about a third of its global production, will last more than a day, the spokesperson added.
Some plants operated by Toyota's affiliates Hino Motors and Daihatsu are included in the shutdown.
Toyota, which has experienced cyber attacks in the past, is a pioneer of Just-In-Time manufacturing with parts that arrive from suppliers going straight to the production line rather than being stockpiled.
State actors have launched cyberattacks on Japanese corporations in the past, including an attack on Sony Corp in 2014, which exposed internal data and shut down computer systems.
The United States blamed North Korea for that attack, which came after Sony released "The Interview", a comedy about a plot to assassinate the regime's leader Kim Jong Un.
Toyota's production halt comes as the world's biggest automaker is already tackling supply chain disruptions around the world caused by the COVID pandemic, which has forced it and other carmakers to curb output.
Toyota this month also saw some production stopped in North America due to parts shortages caused by the Canadian trucker protests.
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