As the number of drivers told to immediately replace airbags continued to climb today, members of Congress called for a criminal investigation into Takata Industries, the Japanese manufacturer of the defective airbag parts being recalled, affecting nearly 8 million cars.

The push by lawmakers came after reports by The New York Times that Takata knew that some of its airbags were exploding too forcibly and had even started testing a decade ago for this, according to claims by two insiders.

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The former unnamed testing engineers told the Times that Takata had started the secret testing in 2004, after the first death from an airbag inflator.

The problem with the airbags - made at plants in Washington state and Mexico - is that the defective inflator can explode with too much force, shattering the metal into shards that, car safety advocates say, are believed to have killed four people.

But after three months, according to the Times, the secret effort was shut down. Technicians were reportedly told to delete data and to dispose of the airbags that had been tested. The report also alleges that technicians were told to not tell regulators.

"What's surprising is not the disclosure of the tests but how long it has taken to get out," said auto-safety expert Sean Kane. "'Cause what we have seen is more than a decade of quality control issues at Takata's plants."

In a statement, Takata said the "anonymous allegations" are "fundamentally inaccurate."

Meanwhile, Honda told tens of thousands of additional car owners to take their vehicles in for airbag replacement.

Honda and Takata are already the subjects of a government investigation. Regulators have asked for documents that will show what the companies knew about the faulty airbags and when they knew it.

Both Takata and Honda said they are cooperating with the government and Honda said it was conducting a third-party review.