Japan's transport ministry raided the headquarters of motor giant Toyota on Tuesday, as a scandal over faulty safety data escalated.
The world's largest carmaker has apologised for providing incorrect or manipulated data for safety certification tests.
The scandal has shaken up the Japanese car industry, with rivals Honda, Mazda and Suzuki also admitting to submitting faulty data.
Toyota sold more than 11 million passenger vehicles in 2023.
It has said the findings do not affect the safety of vehicles already on the road.
The company has suspended the production of three car models - the Corolla Fielder, Corolla Axio and Yaris Cross.
It has also been accused of using modified vehicles during safety collision tests, for vehicles that are no longer in production.
The raids come a day after Toyota chairman Akio Toyoda apologised to customers and car enthusiasts.
He bowed deeply and held the position for a few seconds, which is customary in Japan when companies apologise for wrongdoing.
"We neglected the certification process and mass produced our cars without first taking the proper precautionary steps,” Mr Toyoda said.
Japanese carmakers Honda, Mazda and Suzuki are also due to be inspected by the authorities over the same issue.
Honda said it found wrongdoing on tests related to noise and engine power, but it has stressed that its vehicles are safe to drive.
Mazda has halted the shipments of some cars and said it will bear the cost to its suppliers.
However, the company added that it is not planning on issuing recalls.
The findings also apply to one Suzuki car model that is no longer being produced.
Earlier this year, Toyota urged owners of 50,000 older vehicles in the US to get immediate repairs as airbag inflators made by Takata could explode and kill.
The "Do Not Drive" advisory covered some of the world's biggest carmaker's models from 2003 to 2005.
BBC