Toyota Motor Co said it will suspend operations at all its assembly plants in Japan starting Tuesday afternoon due to a production system failure, while the disruption is likely to halt domestic production by the world's largest automaker.

A spokesman for the company said it was unable to order components due to a malfunction in the production system, adding that it was "not likely caused by a cyberattack" and that the company was investigating the cause.

Toyota suspended operations at 12 of its plants starting this morning, before the company later decided to halt afternoon shift activities at the other two plants that were in operation.

The company said the accident affected Toyota's plants in Japan only (28 production lines), and it was not immediately clear when production would resume.

Toyota shares fell 0.3 percent to 2429,<> yen in early trading on the Tokyo Stock Exchange, before recovering.

A company spokesman said it was not yet clear how much production was lost.

Reuters calculations show that 14 factories together account for about a third of the global production of the company, which is the world's largest automaker by sales.

Toyota's production in Japan rose 29 percent in the first half of the year, the first such increase in two years.

Toyota said the accident affected only its plants in Japan (Reuters)

13500,<> cars per day

Japan's average daily production of the company's brands, excluding Daihatsu and Hino, was about 13,500 vehicles in the first half, based on Reuters calculations for working days excluding holidays.

Operations at Toyota were halted last year when one of its suppliers was hit by a cyberattack. The one-day disruption caused a production loss of about 13,<> vehicles.

Toyota is a leader in timely inventory management, keeping costs low, but it also means disruption in logistics chains can jeopardize production.