Toyota — already dealing with recalls of millions of vehicles for safety problems — may recall its Corolla subcompact after complaints about power steering problems, a senior executive said Wednesday.

Shinichi Sasaki, Toyota's executive in charge of quality control, said in Tokyo that the world's largest automaker was taking the complaints seriously, and although it was considering a recall, the company was still uncertain whether that would be necessary.

The Corolla is the world's bestselling car.

The Corolla is the world's bestselling car and the number of affected vehicles is unclear. In the United States, the Transportation Department's National Highway Traffic Safety Administration has received about 150 complaints from drivers about power steering on 2009 and 2010 Corollas.

Sasaki said the problems might make drivers feel as though they were losing control over the steering, but it was unclear why. He mentioned problems with the braking system or tires as possible underlying causes of the steering problem.

In Canada, Toyota makes the Corolla at its plant in Cambridge, Ont., where it also assembles the Matrix and the Lexus RX350. Together with its other facility at Woodstock, Ont., it employs 6,500 people.

At the same time, CEO Akio Toyoda said he wouldn't be attending U.S. congressional hearings beginning Feb. 24 on the automaker's safety lapses.

Toyoda said Yoshi Inaba, the head of the company's North American unit, was more familiar with the U.S. situation and was the best executive to deal with the hearing.

"I trust that our officials in the U.S. will amply answer the questions," Toyoda told reporters Wednesday. "We are sending the best people to the hearing, and I hope to back up the efforts from headquarters."

Toyota has recalled 8.5 million vehicles globally during the past four months because of problems with sticking gas pedals, floor mats trapping accelerators and faulty brake programming.

Toyoda promised a brake-override system in all future models worldwide that will add a safety measure against acceleration problems that are behind the recent massive recalls.

The system is a mechanism that overrides the accelerator if the gas and brake pedals are pressed at the same time.

'We are not covering up anything, and we are not running from anything'—Akio Toyoda, CEO, Toyota Motor Corp.

"We are not covering up anything, and we are not running away from anything," Toyoda said.

Toyota has also commissioned an independent research organization to test its electronic throttle system and will release the findings as they become available.

Toyota had no immediate comment on the order Tuesday from the safety administration to hand over documents related to its recalls. Transportation officials want to know how long the automaker knew of safety defects before taking action.

The automaker's U.S. unit said in a statement that it "takes its responsibility to advance vehicle safety seriously and to alert government officials of any safety issue in a timely manner.

"We are reviewing NHTSA's request and will co-operate to provide all the information they have requested," it said.

Toyota must respond within 30 to 60 days or face fines. Reports of deaths in the U.S. connected to sudden acceleration in Toyota vehicles have surged in recent weeks, with the alleged death toll reaching 34 since 2000, according to new consumer data gathered by the U.S. government.

U.S. law requires that automakers notify the government within five days of determining that a safety defect exists and that they promptly conduct a recall. Transportation Secretary Ray LaHood has said the government is considering civil penalties for Toyota over its handling of the recalls.