Hours after Toyota's embattled chairman issued an apology for cheating tests on seven models, officials from Japan's transport ministry descended on the offices in Toyota city to probe irregularities in applications for safety certificates.

Production of three Toyota models in Japan - the Corolla Fielder, Corolla Axio and Yaris Cross - has been suspended.

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The testing failures at Toyota, first revealed in January, were wide-ranging and involved collision tests, the testing of airbag inflation and rear-seat damage in crashes.

Engine power tests were also found to have been falsified.

The company has insisted that models built overseas are not affected.

Toyota has a production facility in Derbyshire that makes the Corolla Hatchback and Corolla Touring Sport for the European market.

Sky News has approached Toyota UK for a statement.

Rivals Mazda, Honda, Suzuki and Yamaha are also caught up in the scandal.

A spokesperson for the transport ministry said their respective offices would also be visited as part of the investigation, which has shaken confidence in the country's sprawling automotive sector.

Toyota is the world's biggest maker of cars by production. It had flagged concerns about its own safety procedures after finding flaws in certification processes for its truck division Hino Motors and at Daihatsu two years ago.

'We are not a perfect company'

Group chairman Akio Toyoda told a news conference on Monday: "We sincerely apologise".

He added: "We are not a perfect company but if we see anything wrong, we will take a step back and keep trying to correct it."

The other four firms have reported similar irregular certification testing.

Also on Monday, Mazda halted production of two models, the Roadster and Mazda 2.

It said incorrect engine control software was used in tests.

Mazda also acknowledged violations on crash tests on three discontinued models.

None of the violations brought up in the scandal affect vehicle safety, according to the companies.

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Commenting on the fallout James Hong, head of mobility research at Macquarie, said: "When it comes to actual sales in [the] Japan market, the damage will be manageable or quite small, because consumers basically have no alternatives in Japan."

Proxy advisory firms Institutional Shareholder Services and Glass Lewis have recommended shareholders vote against re-electing Mr Toyoda at Toyota's upcoming annual general meeting.

Analysts have said they expect Mr Toyoda, the grandson of Toyota's founder, to survive the vote.