WASHINGTON (Bloomberg) — Electronic throttle systems are under review by US safety officials as a possible cause of sudden acceleration in Toyota Motor Corp. vehicles, as alleged in at least seven lawsuits.

The agency is also examining the electronics of other automakers in response to complaints, US Transportation Secretary Ray LaHood said yesterday. Among the questions is whether electromagnetic interference from power lines could affect the computerised systems that help run today's vehicles, LaHood told reporters in Washington.

Toyota has said it ruled out electronics as a cause of sudden acceleration that has resulted in recalls of millions of its cars and trucks. The company's credibility would be further damaged if it is proved wrong, said Rebecca Lindland, an analyst at IHS Global Insight.

"Consumers would view that very negatively," Lindland, based in Lexington, Massachusetts, said in a phone interview yesterday. "That group of diehard Toyota loyalists is being chipped away at as each new recall comes out."

The government is also considering civil penalties against Toyota, the world's largest automaker, for its handling of the recalls, according to an official at the Transportation Department, who asked not to be identified while a review of Toyota's actions continues.

LaHood said yesterday he would phone Toyota president Akio Toyoda to be certain his agency "pushed them over the line" so that Toyota is doing all it can to resolve defects.

Separately, the Toyota City, Japan-based carmaker has been ordered by Japan's government to investigate brake-related problems with the latest version of its Prius hybrid car, the nation's transportation ministry said yesterday.

The ministry said it has received 14 complaints related to Prius brakes. It has also asked other carmakers to look into similar reports. Such requests are "routine," said Masaya Ota, an official in the ministry's recall division.

Toyota's American depositary receipts, each representing two ordinary shares, fell $3.06, or 3.9 percent, to $75.12 at 10.01 a.m. in New York Stock Exchange composite trading. The ADRs are down about 18 percent in the past two weeks.

Toyota began shipping steel plates to US dealers on February 1 as a fix for sticky gas pedals that have caused the carmaker to recall about 2.57 million vehicles in the US and Canada.

"We know what the problem is," Jim Lentz, Toyota's president of US sales, said in an interview on Bloomberg Television on February 1. "We have the fix."

The US recall for pedals that stick applies to model years 2009-2010 RAV4, 2010 Highlander and 2008-2010 Sequoia sport-utility vehicles, 2009-2010 Corolla and 2005-2010 Avalon sedans, some 2007-2010 Camry sedans, 2009-2010 Matrix hatchbacks, and 2007-2010 Tundra pickups, according to Toyota.

Toyota also has recalled and plans to fix about 5.6 million Toyota- and Lexus-brand cars and trucks in the US and Canada because of floor mats that might trap gas pedals and cause vehicles to speed out of control. Some Toyota brand vehicles are affected by both types of recalls.

The investigation of the Prius in Japan could undermine sales in Toyota's home market, where it hasn't recalled any vehicles due to the sudden-acceleration issue. The model was Japan's best-selling vehicle in 2009.

"The Prius is Toyota's flagship model, its key to the future," said Ashvin Chotai, managing director of London-based Intelligence Automotive Asia Ltd., a consulting company. "If that model gets tainted, that would suggest Toyota's crisis has moved on to the next level."

In the US, the National Highway Traffic Safety Administration, part of the Transportation Department, hadn't found evidence as of February 1 that anything other than sticky or trapped accelerators caused unintended acceleration, the Transportation Department official said.

Mike Michels, Toyota's US vice president for corporate communications based in Torrance, California, said in an e-mailed statement yesterday that he had "no information" on a continuing investigation by NHTSA of the automaker's electronic throttle control system.

At least 15 lawsuits seeking class action status have been filed against Toyota on the acceleration issue, and seven of them claim an electronic throttle system called ETCS-i is at fault instead of the pedals.

In cars with the ETCS-i system, the engine's throttle is controlled by electronic signals, which are sent from a sensor that detects how far the gas pedal is depressed. The signals are transmitted to a computer module that controls how much the throttle opens.

Lawyers claiming an electronic defect contend that floor mats or stuck pedals don't explain the sudden-acceleration incidents that triggered their lawsuits.

Edgar Heiskell, an attorney from Charleston, West Virginia, who represents the family of a Michigan woman who died when her 2005 Toyota Camry hit a tree at almost 80 miles an hour (129 kilometers per hour), said her car didn't have a floor mat. She stood on the brake, attempting to stop the car after it accelerated from a speed of 25 miles per hour, he said.

The suit was filed in November. Heiskell also has filed a West Virginia suit against Toyota seeking class-action status.

In a Texas lawsuit filed on January 29, plaintiff Alfred Pena said his 2008 Toyota Avalon unexpectedly accelerated at a stop sign on January 14, causing a collision. He wasn't injured, said Robert Hilliard, an attorney representing Pena. Pena's wife, Sylvia, had a previous episode of unintended acceleration that didn't result in an accident, Hilliard said.

Sylvia Pena "was sitting dead still," and the car accelerated as she released the brake before she touched the gas pedal, Hilliard, of Corpus Christi, Texas, said in an interview.