SANTA ANA, Calif. - Toyota Motor Corp. knew of at least six sudden acceleration incidents as early as 2003, including some that were verified by its own technicians and dealers, according to court documents filed Monday as part of sprawling litigation against the Japanese automaker, reported The Detroit News.

The incidents were reported to Toyota and culled from thousands of pages of internal documents that were included in filings made in U.S. District Court in Orange County.

Plaintiffs lawyers allege that the automaker did not respond appropriately to complaints in hundreds of lawsuits filed against Toyota in state and federal court after the automaker began recalling millions of vehicles.

Toyota has recalled more than 9 million vehicles worldwide, including more than 7 million in the United States, mostly to address the risk of unintended acceleration but also to correct other problems ranging from rusting truck frames to brake glitches in the Prius hybrid.

Toyota responded that it had identified two mechanical causes of unintended acceleration and had addressed the problem with "effective and durable solutions" in the recalls. "Toyota rejects claims that plaintiffs suffered economic damages because of the recent recalls," the company said.

"Importantly, to date, plaintiffs have not cited a specific cause that would support their claim of a defect in Toyota's electronic throttle control system," it said in a statement. "No credible scientific theory or proof has been advanced to support this allegation. Toyota firmly believes that the system is completely safe and that reliable scientific evidence will demonstrate the safety of our vehicles in the investigations currently underway and, ultimately, to the court."

Some plaintiffs allege that Toyota's electronic throttle control system is defective.

According to the National Highway Traffic Safety Administration, by the time that Toyota issued major recalls to address the risk of unintended acceleration last fall, the automaker had received 2,000 complaints of unintended acceleration over a decade -- more than other automakers.

The issue is extremely difficult because industry experts say most cases of reported unintended acceleration involve driver error. But Toyota has identified mechanical causes, including loose floormats that can entrap pedals.

It has replaced gas pedals and adjusted the floor space of some vehicles to keep pedals from getting entrapped by loose mats or other materials. It is installing a brake override system in all new and many older models.

One of the new filings seeks class-action status for vehicle owners claiming the value of their cars has diminished because of alleged defects, while the other claims damages for motorists injured or killed in accidents blamed on sudden acceleration.

Specific information about the incidents, however, was barred from public view to protect customers' privacy, and the complaints did not list the dates of problems or the year or the model of each Toyota involved.