US authorities have said the sudden, unintentional acceleration of Toyota cars while driving was not caused by the company's electronic throttle control system as initially suspected, but by driver error.

A series of complaints were made against Toyota cars in the United States in 2009, resulting in the recall of eight million cars.

"There is no electronic-based cause for unintended high-speed acceleration in Toyotas,” US transportation minister Ray LaHood said this week. A year ago he had told a congressional hearing, drivers should stop driving Toyota cars.

Instead it is thought the so called unintentional acceleration was caused by drivers confusing the accelerator and the brake pedal.