(Reuters) - Toyota Motor Corp (7203.T) said on Thursday it would call back 190,000 more vehicles to replace potentially defective air bags made by Takata Corp (7312.T), and Japan's regulator said it may change its recall system to better respond to what it called an "unprecedented" crisis.

The transport ministry, which also acts as the auto industry regulator, told reporters it was considering revising parts of the existing recall system, but gave no details.

"Changing the law would be a lot more involved, but there are things we can change outside the law," said Masato Sahashi, head of the ministry's recall division. "What we're considering is not something that would take as long as a month or two."

In the United States, the auto safety regulator, the National Highway Traffic Safety Administration (NHTSA), has come under fire for not moving quickly enough to ensure wider recalls of cars fitted with possibly defective air bags.

Toyota's recall follows an explosion of a Takata-made air bag inflator in a 2003-model Toyota subcompact at a scrapyard in Japan last month, though the cause of the potential problem is still unknown, the ministry said.

Toyota said it would recall 185,000 vehicles across 19 models including the Corolla and Alphard in Japan, and 5,000 in China, as a preventative measure and to investigate the cause. It said it was not aware of injuries or deaths related to the problem. The vehicles subject to the recall were produced between September 2002 and December 2003.

Toyota said the recall covers vehicles of the same model year as the Will Cypha car that exploded in a scrapyard last month and that were equipped with the same type of inflator. Those inflators were made at Takata's Monclova factory in Mexico, it said.

The Mexican government is requesting information from Takata's local unit to determine which car models have used its products. Takata has until Friday to respond to the request.

Japan's transport ministry said it instructed other automakers to check whether their vehicles could be affected by the same inflator problem. A spokesman for Honda Motor (7267.T), Takata's biggest customer, said the company was looking into the issue, but did not elaborate. Nearly 2.8 million cars have been recalled in Japan, and over 16 million worldwide since 2008.

For the cars being recalled, Toyota said it will replace front passenger-side air bag inflators or disable the air bag system and warn against sitting in the passenger seat if a replacement is not immediately available.

Takata's inflators have been linked to five deaths, in the United States and Malaysia, exploding too forcefully and spraying metal shards inside cars.

Takata this week rejected an order by NHTSA to declare its inflators defective and expand an investigative recall in hot and humid regions to the rest of the country. It said its own data did not support the need for such a move, and that doing so could divert replacement parts from the areas that need them most.

A Japanese ministry official said that if a U.S. regional recall were expanded nationwide, he would expect automakers to take similar action in Japan.

Takata, automakers and regulators are still trying to find out what's causing the air bag ruptures related to the regional recall. Extending that nationwide would add more than 8 million vehicles to the mix, Takata has said.