A US judge has rejected a bid by air bag manufacturer Takata Corp and automaker Honda Motor Co to toss out a class-action lawsuit on behalf of millions of owners with potentially faulty airbag inflators, even as the firms are moving to quickly settle death claims.

The Japanese companies have agreed to undisclosed settlements for six of eight deaths linked to ruptured inflators as U.S. prosecutors ramp up a probe of the ruptures and whether regulators were misled. Four settlements have been reached in recent months.

Litigation arising from four of the six U.S. deaths has been settled, Honda spokesman Chris Martin said. Court records show a fifth U.S. death - in September 2014 in California - has also been settled.

Honda has been working to settle claims quickly, Martin said. "Honda has worked in good faith to quickly resolve the concerns of those families," he said.

Honda, Takata and other automakers will continue to face a class-action suit filed on behalf of millions of owners that alleges Takata and the automakers violated anti-racketeering laws because of a ruling on Wednesday by U.S. District Judge Federico Moreno in Miami.

Since 2008, at least 19.2 million U.S. vehicles have been recalled for inflators that can rupture. The suit claims millions of car owners overpaid for vehicles with faulty airbags and the recalls reduced the value of those vehicles.

"Honda looks forward to the opportunity to properly challenge plaintiffs' claims," Honda's Martin said. He said the automaker is confident that the racketeering claim will be dismissed.

Takata declined to comment on the ruling.

The airbag manufacturer has bolstered its legal team. Lanny Breuer, a partner at Covington & Burling LLP who served as U.S. assistant attorney general overseeing the criminal division from 2009-2013, said in a court filing in November that he was representing Takata in the civil lawsuit.

The previously unreported civil settlements cover five airbag deaths in the United States - including two reported inflator deaths this year in Texas and Louisiana - and a 2014 incident in Malaysia in which a pregnant woman was killed and her baby subsequently died. Judge Moreno approved that settlement on Nov. 20.

U.S. prosecutors have conducted interviews with Takata and Honda employees in both Japan and the United States, two people briefed on the matter told Reuters. The U.S. Attorney's Office in Detroit declined to comment.

Martin declined to say if executives have been interviewed but said "Honda is actively cooperating with the DOJ investigation of Takata."

A federal grand jury has subpoenaed documents from Takata, but Honda said it has not received a grand jury subpoena.

Honda has confirmed seven airbag deaths since 2009. An inflator is also suspected in the 2013 death of a California man in a 2002 Acura TL.