Unintended acceleration in Toyota vehicles may have been a factor in the death of 89 people through the past decade - a substantial increase on previous alleged numbers.
The US' National Highway Traffic Safety Administration said that from 2000 to mid-May, 2010 it had received more than 6200 complaints involving sudden acceleration in Toyota vehicles.
The reports included 89 deaths and 57 injuries over the same period. Previously 52 deaths were suspected of being connected to the problem but most remain merely allegations.
Toyota has, however, recalled more than eight-million vehicles worldwide since late 2009 in connection with accelerators, floor mats and brakes. It has also paid a record $16.4-million fine for its allegedly slow response to an accelerator pedal recall and is facing hundreds of state and federal lawsuits.
The company did not admit any fault.
Toyota said in a statement: "We sympathise with the individuals and families involved in any accident involving our vehicles. We are making an all-out effort to ensure our vehicles are safe and we remain committed to investigating quickly reported incidents of unintended acceleration in our vehicles.
"Many complaints in the NHTSA database, for any manufacturer, lack sufficient detail that could help identify the cause of an accident. We will continue to work in close partnership with law-enforcement agencies and federal regulators with jurisdiction over accident scenes whenever requested."
The US Congress is now considering upgrading auto safety laws to stiffen potential penalties against automakers, give the US government more powers to demand a recall and push car companies to meet new safety standards.
Toyota's US sales chief, Jim Lentz, told Congress last week that dealers had made changes to nearly 3.5-million vehicles under the recall and that the company and its dealers had conducted 2000 vehicle inspections.
He reiterated that there was no evidence that electronics were to blame for the reports of alleged sudden acceleration.
NHTSA administrator David Strickland told lawmakers the agency had spoken to nearly 100 vehicle owners who said they had experienced unintended acceleration after a recall fix had seen no "pedal entrapment" or "sticky accelerators" in any vehicle that had been attended to correctly.
The US government is investigating acceleration problems in Toyotas and a separate 15-month study by the National Academy of Sciences is scheduled to begin in July, 2010. - Sapa-AP