TOKYO - Japan's government is investigating 38 previously reviewed reports of unintended acceleration by Toyota Motor cars in Japan in response to the concerns over the company's safety record.

Toyota has recalled the Prius and other hybrid vehicles in Japan due to a braking glitch but the acceleration problem has cantered on the U.S. market and not yet been raised as a major issue for cars sold in Japan.

Transport Minister Seiji Maehara said the regulator had conducted routine reviews of 134 cases of unintended acceleration between 2007 and 2009, 38 of which involved Toyota cars, a proportion in line with its overall market share.

But Japan's transport regulator has decided to take another look into those cases in light of the increased scrutiny of the issue. The probe will focus on Toyota but also include other maker's cars, Maehara said.

"The number of complaints about Toyota cars is not out of proportion to its share of the overall number of vehicles registered," Maehara told reporters. "But given the ongoing issue, we would like to investigate Toyota cars."

Maehara said the 134 cases were part of 15,000 or so auto-related problem cases brought to the regulators' attention between 2007 and 2009.

At a congressional hearing on Tuesday Toyota's top-ranking U.S. executive, Jim Lentz, said 70 per cent of complaints about unintended acceleration remained unexplained.