TOKYO -- Toyota Motor and Nissan Motor are recalling more than 6.5 million cars globally to replace potentially faulty airbag inflators made by Takata Corp.

Toyota said today it would recall about 5 million Corolla, Vitz/Yaris and other models worldwide to replace Takata airbag inflators.

The recall involves 35 models including 1.36 million cars in Japan, 1.27 million in Europe, 637,000 in the U.S. and 18,000 in Canada, the company said in an email.

U.S. National Highway Traffic Safety Administration spokesman Gordon Trowbridge said Toyota and Nissan as well as Japanese government officials have been in contact with the U.S. safety agency over the last few days, and NHTSA will soon announce "significant new steps" related to accelerating Takata recalls.

"While precise root cause remains undetermined, the clear association with high humidity has suggested that moisture and time are factors in this defect," Trowbridge said.

Asked about the latest recalls, a Takata spokeswoman said a probe into the causes for the airbag defects was ongoing and that the company continued to cooperate with the automakers.

Toyota said it will replace the affected front driver-side airbag inflators with newly manufactured parts produced by Daicel Corp. Takata will supply the replacements for front passenger-side airbag inflators because compatible parts from a different supplier are not available, Toyota said.

No accidents or injuries have been reported, a Toyota spokeswoman said, adding that the recall was for investigative purposes. Cars with production dates from March 2003 to November 2007 are subject to the recall.

Nissan said it was recalling about 1.56 million cars globally over the same issue, adding that no accidents or injuries had been reported.

Nissan's recall includes 563,000 cars in Europe, 326,000 in North America, 288,000 in Japan and 274,000 in China. The company did not give details about the models affected.

Nissan will begin notifying customers in June, said Dion Corbett, a company spokesman.

Six fatalities in Honda cars, including five in the U.S. and one in Malaysia, have been blamed on shrapnel from Takata airbags. At least 105 injuries are connected to the flaw, U.S. Senator Bill Nelson said last month.

Honda today said it was preparing to file additional recalls related to Takata airbags. The company did not specify which models or regions the recalls would affect.

An American Honda spokesman said in a statement that the automaker was "not considering additional actions in the United States related to the Toyota and Nissan airbag inflator announcements made today in Japan."

Today's announcements raise the number of vehicles recalled worldwide since 2008 over Takata airbag inflators to roughly 31 million since 2008, according to Reuters estimates.

Takata faces multiple class action lawsuits in the United States and Canada, as well as a U.S. criminal investigation and a regulatory probe.

Moisture intrusion

Toyota has already recalled vehicles in regions with high humidity such as the Gulf Coast in the U.S.

Toyota said today that certain types of airbag inflators were found to have potential for moisture intrusion and could be susceptible to abnormal deployment in a crash though the relationship between the two is not known.

"The biggest problem here is both carmakers and Takata have not specified the direct reason for the defect," said Takeshi Miyao, an analyst at researcher Carnorama in Tokyo. "They can't recall all the possible cars without knowing what the direct cause is as the costs are enormous and they don't know which side should cover the costs."

Regulators in Japan and the U.S. are investigating Takata airbag inflators that may malfunction, deploying them with so much force that the part breaks and hurls metal shrapnel at the car's occupants.

A group of 10 automakers hired aerospace and defense company Orbital ATK to test potentially faulty Takata airbag inflators. The Japanese component maker has also commissioned German research group Fraunhofer Society to investigate the cause of airbag ruptures.

Takata, which has forecast a return to profit this fiscal year, has said it's unable to estimate the penalties from the lawsuits associated with the airbags and hasn't set aside any amount to cover them as the cause of the defect is still being investigated.

Hans Greimel, Reuters and Bloomberg contributed to this report.