Toyota said Monday it was suspending shipments of 10 models that use engines linked with testing irregularities at an affiliate company.

The affiliate, Toyota Industries, did not conduct proper horsepower output testing for the certification of three diesel engine models, the parent group said.

The automaker said the models, including the Land Cruiser 300 and HiAce, use the affected engines.

The shipment suspension will affect about 36,500 Toyota vehicles produced every month, the company said.

Toyota Industries said in a separate statement that its workers adjusted the fuel injection amounts to make the data "better-looking".

Toyota Motor said it had since confirmed that the affected engines and vehicles meet engine performance output standards, meaning there was no need to stop using them.

Toyota Industries also said other irregularities were found in connection with the certification process for engines for forklifts and other construction equipment.

Toyota Industries reported its findings to the transport ministry, which said it planned to carry out its own inspections.

The news comes after Toyota subsidiary Daihatsu, which produces popular small vehicles in Japan, had to suspend all shipments last month after it disclosed that it had not properly conducted vehicle safety tests for decades.