WASHINGTON – The government is seeking to fine Toyota a record $16.4 million, accusing the Japanese auto giant of hiding a “dangerous defect” in its slow reporting of faulty gas pedals that have been blamed for unintended sudden accelerations and motorist deaths.

The proposed fine, announced Monday by Transportation Secretary Ray LaHood, is the most the government could levy for the sticking gas pedals, which have led Toyota to recall millions of vehicles. There could be further penalties under continuing federal investigations, and Toyota also faces private lawsuits seeking many millions more.

Toyota Motor Corp. has recalled more than 6 million vehicles in the U.S., and more than 8 million worldwide, because of acceleration problems in multiple models and braking issues in the Prius hybrid.

Documents obtained from the Japanese automaker show that Toyota knew of the problem with the sticking gas pedals in late September but did not issue a recall until late January, LaHood said. The sticking pedals involved 2.3 million vehicles.

“We now have proof that Toyota failed to live up to its legal obligations,” LaHood said in a written statement. “Worse yet, they knowingly hid a dangerous defect for months from U.S. officials and did not take action to protect millions of drivers and their families.”

For those reasons, LaHood said, the government is seeking a fine of $16.375 million, the maximum penalty possible. That dwarfs the previous record: In 2004, General Motors paid a $1 million fine for responding too slowly on a recall of nearly 600,000 vehicles over windshield wiper failure.

Toyota did not say whether it would pay the fine. The automaker has two weeks to accept or contest the penalty.

“While we have not yet received their letter, we understand that NHTSA has taken a position on this recall,” the company said in a written statement, a reference to the National Highway Transportation Safety Administration. “We have already taken a number of important steps to improve our communications with regulators and customers on safety-related matters as part of our strengthened overall commitment to quality assurance.”

The company noted that it has appointed a new chief quality officer for North America and has given its North American office a greater role in making safety-related decisions.

Under federal law, automakers must notify NHTSA within five days of determining that a safety defect exists, and must promptly conduct a recall.

The Transportation Department said the fine it is seeking is specifically tied to the sticking pedal defect, and the car manufacturer could face additional penalties if warranted by investigations.

The government has linked 52 deaths to crashes allegedly caused by accelerator problems in Toyotas. The recalls have led to congressional hearings, a criminal investigation by federal prosecutors, dozens of lawsuits and an intense review by the Transportation Department.

Toyota has attributed the problem to sticking gas pedals and accelerators that can become jammed in floor mats. Dealers have fixed 1.7 million vehicles under recall so far.

Consumer groups have suggested that electronics could be the culprit, and dozens of Toyota owners who had their cars fixed in the recall have complained of more problems with their vehicles surging forward unexpectedly. Toyota says it has found no evidence of an electrical problem.

Reviews of some recent high-profile crashes in San Diego and suburban New York have failed to find either mechanical or electronic problems. In the New York case, a police investigation found that the driver, not the car, was to blame.

After the recalls, the Transportation Department demanded in February that Toyota turn over documents detailing when and how it learned of the problems with sticking accelerators and with floor mats trapping gas pedals.

NHTSA said documents provided by Toyota showed the automaker had known about the sticky pedal defect since at least Sept. 29, 2009, when it issued repair procedures to distributors in 31 European countries and Canada to address complaints of sticking pedals, sudden increases in engine RPM and sudden vehicle acceleration.

The government said the documents also show that Toyota knew that owners in the U.S. had experienced the same problems. Toyota has provided NHTSA with more than 70,000 pages of documents during the investigation.