Ray LaHood, the Transportation secretary, said Wednesday morning during a House Appropriations panel hearing that owners of recalled Toyotas should stop driving them and take them to their dealers to be repaired.

Mr. LaHood said his advice to owners of recalled Toyotas was to “stop driving it, take it to a Toyota dealer because they believe they have a fix for it.”

“We need to fix the problem so people don’t have to worry about disengaging the engine or slamming the brakes on or put it in neutral,” Mr. LaHood said in response to questions.

His comments at the hearing, which appeared to be off the cuff, came shortly after he told reporters that he planned to call the president of Toyota, Akio Toyoda, about the recalls and after the Japanese government told the carmaker to examine the brakes on its hybrid Prius. Drivers in Japan and the United States have complained that the brakes momentarily stopped working when driving at low speeds.

“I’m going to take the initiative to have a conversation with Mr. Toyoda very soon, to talk to him about how serious this is, and to make sure that he understands,” Mr. LaHood said. “I think he understands, but I’ve never talked to him. I just feel like I need to have a conversation with him.”

Mr. LaHood’s comments Wednesday were the latest in an aggressive campaign by his department over the Toyota situation. Last week, Mr. LaHood took credit for the company’s decision to stop building and selling eight models involved in a recall over accelerator pedals that could potentially stick, saying Toyota did not take the step until urged to do so by the department.

Some safety advocates said however that Mr. LaHood might be trying to protect federal safety regulators from potential liability issues over their role in investigating defects.

Mr. LaHood told reporters that regulators have the resources and expertise to conduct a thorough review of consumer complaints regarding unintended acceleration in Toyota focusing on electronic throttles. The National Highway Traffic Safety Administration “is not finished with this safety issue involving Toyota,” he said, explaining that the department would look into the possibility of electromagnetic interference with the accelerator system.

“I think at the department, we will continue to look at the electronics, continue to study that, continue to work with Toyota on that, and then make a judgment about that,” Mr. LaHood said.

He confirmed Wednesday that the Transportation Department was considering a civil penalty against Toyota over the handling of the recalls.

Toyota had no immediate response to Mr. LaHood’s comments. The company’s shares on Wall Street were down 7.2 percent.

Lawmakers and the Transportation Department have stepped up pressure on Toyota, seeking proof that problems that could cause its cars to speed up unexpectedly were limited to floor mats and sticking pedals.

In a letter to James E. Lentz III, the president of Toyota Motor Sales U.S.A., Representatives Henry A. Waxman and Bart Stupak asked the automaker to provide documents showing that the computer systems on its cars were not at fault — something Toyota has vigorously denied.

Mr. Waxman is the chairman and Mr. Stupak a subcommittee chairman of the House Energy and Commerce Committee.

Mr. LaHood said in a statement Tuesday that Toyota had announced the recalls only after department officials flew to Japan “to remind Toyota about its legal obligations.”

In a statement, Toyota said it had received and was reviewing the committee’s letter.

“We will of course cooperate with the committee’s inquiry,” Martha Voss, a Toyota spokeswoman, said. She did not comment on Mr. LaHood’s statement.

As it worked on solutions to the acceleration problem, Toyota has said that computers on its cars were not at fault.

But lawyers, safety advocates and consumers continue to raise questions about the cars’ electronic systems, which they say could cause a car’s throttle to stick. Toyota faces 11 class-action lawsuits over accidents involving the defect.

In their letter, Mr. Waxman, Democrat of California, and Mr. Stupak, Democrat of Michigan, told Mr. Lentz that statements he had made in interviews appeared to contradict information Toyota officials gave to committee staff members in a meeting last week. The Energy and Commerce Committee plans a hearing late this month to explore two recalls of Toyota vehicles related to reports of cars speeding up unexpectedly.

The House Committee on Oversight and Government Reform plans its own hearing on Toyota next week. Mr. LaHood is expected to testify, as is Yoshimi Inaba, the chief executive of Toyota’s North American operations.

On Monday, the company announced a remedy meant to prevent accelerator pedals from sticking on 2.3 million vehicles in the United States. Toyota also has recalled more than five million vehicles because their floor mats could become stuck in floor pedals.

In a conference call with journalists on Monday, and in interviews on NBC, CNBC and ABC, Mr. Lentz emphasized that Toyota was confident its fixes would solve the problem.

“It is not an electronics issue,” Mr. Lentz said.

In response, the Energy and Commerce Committee asked Toyota to submit documents supporting the claim as well as information that might counter it. It is seeking the documentation by Friday. In the letter, Mr. Waxman and Mr. Stupak also took issue with Mr. Lentz’s comments that Toyota first knew of sticking gas pedals in late October.

During a meeting with committee staff members on Jan. 27, Toyota officials said they first learned of this problem through reports of sticking pedals in vehicles in England and Ireland in April or May 2009.

In August, Toyota began production changes on models sold in Europe, and it recalled 1.8 million vehicles there last week for the pedal problem. They will receive the same repairs as cars sold in America, a Toyota Europe spokesman said.

The letter asked Toyota to clarify when it first learned of the problem and any action that might have been taken.

The representatives also made note of Mr. Lentz’s comments Monday in which he expressed confidence that the repair to the Toyota vehicles “is going to stop what’s going on.”

In the meeting with committee staff members, Mr. Waxman and Mr. Stupak said company officials had said the causes of sudden acceleration were “very, very hard to identify.”

The statements by Mr. LaHood came as he criticized the company Tuesday in an interview with The Associated Press.

Mr. LaHood contended that federal safety officials, in the meeting with Toyota in Japan, had to “wake them up” to the seriousness of the situation.

Last week, Mr. LaHood contended that pressure from his department was the reason Toyota had decided to stop building and selling eight models involved in the recall for sticking pedals. Toyota initially said the action came voluntarily.

“They should have taken it seriously from the very beginning when we first started discussing it with them,” Mr. LaHood told The A.P. “Maybe they were a little safety deaf.”

However, the federal safety agency faced its own criticism Tuesday from the Center for Auto Safety, a consumer group.

It said federal documents on Toyota acceleration cases did not give a clear picture of how the agency had conducted investigations, or what the results had been.

“Toyota unintended acceleration to date raises more questions than answers,” Clarence Ditlow, the group’s executive director, said in a statement.