TOKYO — Mazda is expanding its U.S. recall for Takata air bags that may explode to the entire country, following Japanese rival Honda in the decision.

Mazda Motor Corp. said Wednesday it will officially notify the U.S. National Highway Traffic Safety Administration soon, but was still compiling details including the exact vehicle numbers requiring recall.

NHTSA is demanding nationwide air bag recalls. The recalls have concentrated on regions with high humidity, which is suspected as factor in the explosions.

So far the Mazda recalls for driver side air bags total about 87,000 vehicles. Making the recall nationwide would likely lift that number to 330,000 vehicles.

Japanese supplier Takata Corp. is under fire for air bag inflators that can explode, shooting out metal and plastic pieces. At least five deaths and dozens of injuries have been linked to the problem worldwide.

Takata has refused the NHTSA demand for nationwide recalls, although it has said it will co-operate with automakers who decide to do them.

Honda Motor Co. said this week that it will comply with the NHTSA demand, adding 2.6 million more vehicles to its recall, which will now total 5.4 million vehicles.

But Honda is calling it a safety improvement campaign to address customer concerns, not because the product is defective.

Mazda is also saying it is unclear whether theres a defect but it will carry out the recall to investigate.

Although Takata has found production errors and other defects, the root cause of the explosions has not yet been pinpointed.

Meanwhile, for passenger-side air bag inflators, NHTSA says that recalls remain limited to high-humidity areas because theres no data to suggest a problem with them nationwide.