The U.S. government says it will seek the maximum penalty of $16 million US from Toyota Motor Corp. for failing to promptly notify regulators about defective gas pedals in its vehicles.

Transportation Secretary Ray LaHood said the National Highway Traffic Safety Administration has documentation obtained from Toyota that the carmaker knew about the "sticky pedal" problem in some of its vehicles in late September but did not recall cars until late January. Carmakers are required to notify the agency within five business days of detecting a safety defect in vehicles.

"We now have proof that Toyota failed to live up to its legal obligations," LaHood said in a release. "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.”

The $16.38-million fine would be the largest civil penalty ever issued to an automaker by the government.

In a statement Monday, Toyota, which has two weeks to accept or contest the fine, did not say whether it would pay.

"While we have not yet received their letter, we understand that NHTSA has taken a position on this recall," Toyota said. "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."

Toyota mentioned its appointment of a new chief quality officer for North America and the greater role for its North American office in making safety-related decisions.

More penalties possible

On Feb. 16, the National Highway Traffic Safety Administration launched an investigation into the timeline and scope of Toyota recalls and required the automaker to turn over documents and explanations related to its adherence to U.S. auto safety laws.

The NHTSA made a preliminary determination on the fine announced Monday based on a review of documents Toyota has provided, the agency said.

So far, Toyota has submitted more than 70,000 pages of documents, which NHTSA officials are still reviewing.

The U.S. Transportation Department said the penalty being sought against Toyota is specifically tied to the sticking pedal defect, and that Toyota could face additional penalties under the government's continuing investigation.

The government has linked 52 deaths to crashes allegedly caused by accelerator problems in Toyotas. Toyota attributes the problem to sticking gas pedals and accelerators that can become jammed in floor mats and has cited no evidence of an electrical problem.

The company has recalled more than six million vehicles in the United States and more than eight million worldwide, including 270,000 in Canada, because of acceleration problems in multiple models and braking issues in the Prius hybrid. Toyota dealers have worked on 1.7 million vehicles under recall so far.

The recalls have led in the U.S. to congressional hearings, a criminal investigation by federal prosecutors, dozens of lawsuits and the intense review by the Transportation Department.

With files from The Associated Press