Toyota Motor recalled nearly 2.2 million vehicles, citing a defect that could cause gas pedals to stick, in an extension of the safety crisis that has hounded the world’s top automaker for more than a year.

The surprise action on Thursday extended a damaging string of recalls covering 19 million Toyota vehicles worldwide since 2009, mainly over complaints of unintended acceleration linked to defective floormats and gas pedals.

The additional recalls covered several Toyota and Lexus models and renewed questions about quality at the world’s largest automaker and its ability to shake the stubborn safety crisis that has undermined sales and tarnished its brand.

The total of Toyota vehicles recalled in the United States on Thursday topped the nearly 1.8 million cars and trucks that the top global automaker sold here in 2010.

The new recalls come just over two weeks after U.S. safety regulators cleared Toyota by announcing that a 10-month study had concluded that the company’s electronic controls were not to blame for reported episodes of runaway acceleration as safety advocates and some members of Congress had suspected.

“They want to put this behind them,” said Scott Painter, chief executive of auto buyer resource TrueCar.com. “They have been affected financially and are trying to get customers back.”

Toyota’s U.S. market share fell from 17 percent at the end of 2009 to just more than 15 percent in December 2010. It has been forced to discount more heavily to attract buyers.

Painter said the new recall could have a short-term chill on buyers but will help Toyota over the long term, especially since Thursday’s development was followed by a statement from regulators that they have concluded their investigation of the matter.

Toyota shares fell 7 cents to close at $90.10 on the New York Stock Exchange.

Shuba Srinivasan, a marketing expert at Boston University School of Management, said Toyota was taking a step “in the right direction” to regain public trust and rebuild its brand.

Mike Rozembajgier, vice president of recalls for ExpertRECALL, said Toyota will continue to be under the safety spotlight and must be “extra cautious to ensure that they’ve got the appropriate recall plans in place.”

NHTSA CLOSES TOYOTA PROBE

The latest recalls address the risk that loose floormats of carpeting could jam the gas pedal and cause unintended acceleration on six Toyota and Lexus models.

Toyota said its decision to widen initial recalls stemmed from its ongoing conversations with the National Highway Traffic Safety Administration.

NHTSA chief David Strickland said the agency has reviewed more than 400,000 pages of documents since last spring to determine whether the scope of Toyota recalls was sufficient.

“As a result of the agency’s review, NHTSA asked Toyota to recall these additional vehicles, and now that the company has done so, our investigation is closed,” Strickland said.

Toyota spokesman John Hanson said there had been no consumer complaints that spurred the action. Toyota said it was unaware of any injuries or accidents stemming from these recalls.

“What we’re trying to do is make sure we’ve captured any vehicles that could have a problem like this,” Hanson said.

Safety advocates remain skeptical the matter is finished.

“The reality is there are a continuation of problems that are going to haunt the company until they get to the real root of the issue,” said Sean Kane, president of Safety Research & Strategies, Inc.

Kane’s group assists plaintiffs attorneys, including cases against Toyota. The company faces lawsuits over sudden acceleration with potential liability of $10 billion.

Hanson said the new recalls have dissimilar causes, including 1.4 million vehicles for loose floormats that can jam the accelerator.

This covered 761,000 RAV4 crossovers for the model years 2006 through 2010, 603,000 4Runner crossovers for the model years 2003 through 2009, and about 17,000 Lexus LX 570 vehicles for the model years 2008 through 2011.

Toyota also recalled 372,000 RX 330, RX 350 and RX 400H vehicles as well as 397,000 Highlander and Highlander HV vehicles because retention clips that hold down the carpet on the driver’s side could come loose after service and affect the accelerator pedal.

About 20,000 Lexus GS 300 and GS 350 all-wheel drive vehicles were recalled to change the shape of a plastic pad embedded in the driver’s side floor carpet.

The company also recalled 99,000 Highlanders and RX family models for carpet clips outside the United States.