All 28 vehicle assembly lines at Toyota’s 14 car plants in Japan shut down on Tuesday due to a problem in the computer system that deals with incoming parts.

The company does not believe the issue was caused by a cyber attack but the cause is still under investigation, said spokeswoman Sawako Takeda.

It was unclear when the lines would be able to resume work.

Toyota declined to say which models might be affected.

The shutdown comes after a shortage of computer chips and other parts stalled production in Asian nations affected by social restrictions over the coronavirus pandemic.

The chips shortage problem had only recently started to ease for Japan’s top car maker, which makes the Camry sedan, Prius hybrid and Lexus luxury brand.