The scrutiny comes as company President Akio Toyoda isfrom American lawmakers Wednesday over the recalls of 8.5 million vehicles.
Transport Minister Seiji Maehara told reporters Wednesday the government will look into the cases filed in Japan from 2007 through 2009. Ministry official Kazumi Furukawa said the investigation will include suspected unintended acceleration involving vehicles produced by other automakers, totaling 134 cases.
No deaths or injuries have been reported, and Toyotas make up about 28 percent of the complaints, about the same as the company's Japanese market share, he said.
Toyota has previously said Japanese models use a different supplier, and are unaffected by the massive overseas recalls for sticky pedals and faulty floor mats. Calls to Toyota in Tokyo went unanswered late Wednesday.
The causes of the acceleration reported in Japan are still unclear, Furukawa said. The government was aware of the reports previously, but decided to carry out a more serious study, he said.
"It has emerged as a big problem in the U.S., and people in Japan are also worried," said Furukawa.
In the U.S., Toyota drivers have complained of their vehicles speeding out of control despite efforts to slow down, sometimes resulting in deadly crashes. The U.S. government has received complaints of 34 deaths linked to sudden acceleration of Toyota vehicles since 2000.
Congressional panels are asking whether modern computerized electronics can make vehicles less safe.
The only Toyota models recalled in Japan since the recall crisis began in October in the U.S. have been the Prius and two other hybrids for an antilock braking glitch.
Toyota has said its experimental plug-in hybrid, a model with limited use, will also need a similar fix.
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