Toyota Motor Corp, seeking to reduce its risk from potentially lethal Takata Corp air-bag inflators, will buy millions of the component from smaller parts maker Nippon Kayaku Co, Reuters reported citing people familiar with the matter.

The Japanese carmaker asked the second-tier supplier last month to increase production so it can supply Toyota with more than 13 million inflators from next July until 2020, said a person with direct knowledge of the deal and a second individual who was briefed on it, according to Reuters.

The move is the most proactive yet by manufacturers in what has become the world's biggest automotive recall. More than 10 automakers have recalled tens of millions of vehicles since 2008 to replace Takata air bags, which have been linked to the deaths of eight people and more than 100 injuries.

Defective Takata air-bag inflators have exploded with excessive force, spraying shrapnel inside vehicles. Automakers are bearing the cost of most recalls while the root cause is investigated.

Toyota based the amount of Nippon Kayaku purchases on the number of vehicles with Takata-made inflators it thinks could become dangerous as the cars age over the next few years, the people said.

If Toyota switches to Nippon Kayaku inflators, it "will replace the high-risk ones, in other words the older ones, first and then proceed sequentially" to newer inflators, one individual said.

Takata has said long-term exposure to heat and high humidity can make its air bags deploy too forcefully. All the vehicles recalled so far are at least five years old.

Toyota asked Nippon Kayaku - a century-old company that also manufactures chemicals and pharmaceuticals - to expand its production facilities to meet the demand, said the sources, who asked not to be named because the discussions are confidential.

The sources, according to Reuters, declined to say how much the purchases would cost Toyota, but average inflator prices suggest a total of around $100-$150 million.

Toyota considers a switch to Nippon Kayaku inflators to be precautionary, in case further recalls are required, said the person with direct knowledge of the deal. Toyota, which has to date recalled more than 12 million vehicles with Takata-made air bag inflators, is a pioneer of lean manufacturing and keeps minimal inventory to reduce costs and improve efficiency.

After being criticized for acting too slowly in its own major recall crisis five years ago, Toyota - which vies with Volkswagen as the world's biggest carmaker - wants to be able to replace at-risk inflators promptly if it needs to, the sources said.

The move does not mean Toyota will stop buying Takata inflators, one of the individuals said. Toyota "won't do anything to crush Takata," he added.

The person with direct knowledge of the deal would not say whether Toyota is helping Nippon Kayaku pay for its expansion, or whether Toyota would keep buying its inflators after 2020, according to Reuters.

Nippon Kayaku employs almost 5,200 staff on a consolidated basis. Total group sales in the year to end-March rose 1.1 percent to nearly 162 billion yen ($1.3 billion).

Previously Honda Motor Co helped Daicel Corp finance a production increase to meet demand for replacement air bags, said a person familiar with that deal. Sweden's Autoliv Inc has also boosted production of replacement inflators at automakers' requests.