The transport ministry Tuesday inspected Mitsubishi Motors Corp. to examine the manufacturer's remedial efforts following a government warning issued last week over its "passive" stance regarding the recall of potentially defective cars.

Officials of the Ministry of Land, Infrastructure, Transport and Tourism conducted an on-site inspection based on the Road Transport Vehicle Law at the automaker's headquarters in Tokyo and its quality management unit in Aichi Prefecture.

According to the ministry, Mitsubishi Motors obtained information on minivehicle oil leaks in 2005, but did not file for a recall until November 2010. The automaker also played down the defect in a report submitted to the ministry.

Since the initial action in 2010, Mitsubishi Motors expanded the scope of models subject to the recall over three times this year on the same potential engine oil leak after someone blew the whistle.

The four recalls cover around 1.76 million units — the most ever recalled in Japan on account of a single defect type — of the Minicab, Town Box, eK-WAGON, and seven other minivehicle models.

According to the filing, the oil leak is apparently caused by a dislodged rubber engine seal, and the engine may burn out.

The automaker has come under fire more than once for covering up consumer claims about potential defects since 2000. In July 2000, the company admitted covering up claims from consumers by offering repairs privately for around 30 years.

In January 2002, a defective hub caused a wheel to fly off a Mitsubishi Motors truck in Yokohama. It struck and killed a woman and hurt her two kids.