Toyota, the world's number one carmaker, has said it is recalling another one million vehicles sold in the United States, a day after suspending the sale of eight models amid worries over a potentially faulty accelerator pedal.

The Japanese auto giant said it found problems with pedals and floor mats, dealing the company a fresh blow as it struggles to salvage its safety reputation.

Thursday's announcement takes the number of cars recalled by the company since November to nearly six million.

The recall affects five models – the 2008-2010 Highlander, 2009-2010 Corolla, 2009-2010 Venza, 2009-2010 Matrix, and 2009-2010 Pontiac Vibe – Toyota said.

A day earlier the company said it would suspend US sales of eight models, including the top-selling Camry, to fix or replace faulty gas pedals that could get stuck.

Last week, Toyota issued a recall for the same eight models, affecting 2.3 million vehicles, which it said had problems related to worn pedal mechanisms that increase friction in certain conditions and can cause the accelerator to stick.

'Engineering probe'

On Wednesday Mike Michels, a Toyota spokesman, said the company was not in a position to discuss the mechanics of the pedal and the possible causes of the problem "because the engineering investigation is ongoing".

Meanwhile Ray LaHood, the US transportation secretary, told Chicago-based WGN Radio that government regulators had asked Toyota to stop production of affected models while it investigated the problem.

Toyota has informed safety regulators that it will consider modifying or replacing accelerator pedals, or modifying vehicle floors on some models.

"Initially, dealers will be instructed on how to reshape the accelerator pedal for the repair," the company said in a notification to the US National Highway Traffic Safety Administration.

"As replacement parts...become available, they will be made available to the dealers."

CTS Corp, the supplier of the accelerator pedals at the centre of the crisis, said late on Wednesday it had a fix for the safety issue and had begun to ship redesigned parts to Toyota factories.

Toyota is also halting production at six plants in the United States and Canada for the first week of February.

The company said its decision to shut down production next week would idle about 14,000 workers.

Financial fallout

Mike Goss, a Toyota spokesman, said those workers would remain employed and would work on plant improvements while assembly lines are shut down.

On the Tokyo stock exchange Toyota shares fell 1.8 per cent on Thursday, after falling by more than four per cent a day earlier as concern deepened about the knock-on effects from the recall.

Analysts said the financial damage to Toyota from the recalls would depend on how long it has to shut production on key models and how badly consumer confidence is shaken.

"It's a devastating blow to Toyota and Toyota's reputation," said Dennis Virag, the president of the Automotive Consulting Group.

"Toyota is the new General Motors in terms of experiencing quality glitches, over-expansion and the proliferation of new product models."