(Reuters) - Honda Motor said it will expand an 'investigative' recall to replace potentially lethal Takata Corp air bag inflators across the globe, taking the total Takata-related recall tally of all brands to more than 19 million since 2008.

Honda earlier added about 2.6 million cars in the United States when it expanded nationwide a recall of driver-side air bag inflators that was previously limited to 11 states and territories with hot and humid climates.

Honda is working out which models and how many vehicles would be covered under a similar recall in other markets, a spokeswoman said on Tuesday.

Takata's air bag inflators have been found to rupture and shoot metal shards into the vehicle, and have been linked to five deaths.

As consumer concerns grow over the safety of Takata air bags, the U.S. National Highway Traffic Safety Administration (NHTSA) last month ordered the supplier to take nationwide a recall of certain driver-side inflators that had been limited to areas of high humidity.

Takata has refused, challenging NHTSA's legal authority to order such a recall when the cause behind the unusual deployment of its air bags is still unknown.

Given Takata's response, Honda's U.S. unit said on Monday it would voluntarily expand its regional recall to cover a total 5.4 million vehicles across the United States.

On Tuesday, Honda said it would recall more than 134,000 cars in Japan covering six models made between 2002 and 2013 that carry Takata driver-side air bags subject to the wider recalls in the United States. Honda will begin the recall in Okinawa, an island in southern Japan, at the end of the month.

Japan's transport ministry has said that about 200,000 vehicles from Honda and Mazda Motor Corp would be subject to an expanded recall in Japan. Mazda is still considering whether to follow suit.

Unlike NHTSA, Japan's regulator cannot order a recall unless the cause of the problem is known. Transport Minister Akihiro Ohta said the ministry would see whether it should change the law to be able to force an 'investigative' recall after gauging the current series of Takata-related recalls, but added there were no immediate plans.

Several automakers have called back millions of cars in the United States to replace Takata-made inflators and investigate the root cause of the problem in what is called a Safety Improvement Campaign, which is different from a typical recall to address known defects.

Takata is struggling to make replacement parts fast enough, and has forecast a loss this business year amid an escalating recall crisis.

The Nikkei business daily on Tuesday quoted Honda CEO Takanobu Ito as saying the automaker would step in to support Takata if needed, but Honda said he was not specifically referring to financial aid.