A Toyota Motor Corp official admitted on Tuesday that the car company was well aware of the Lexus' engine problem some two years earlier but instead of issuing a recall, it merely ordered the replacement of the spring part to correct what the company assumed then as an isolated manufacturing issue.

Yet this week, Toyota started a global recall of its luxury line of Lexus and Crown models to replace their flawed valve springs, which are crucial engine components and could possibly cause vehicles to stall when deemed defective.

Toyota said that vehicles made after August 2008 are not affected by the recall since the company had already shifted to a thicker spring part around that time.

Company spokesman Hideaki Homma told the AAP that the company initially thought that the problem was caused by a foreign substance which might have intruded into the valve springs during the process of manufacturing.

Mr Homma stressed that "we changed the part in August because then the problem won't happen at all, even if tiny particles enter during manufacturing and we are talking about microscopic particles here."

However, customer complaints started mounting and Toyota eventually conceded that the issue was a design defect and was forced to make a global recall of up to 270,000 affected vehicles.

The company vowed to fix the problem expeditiously, seemingly aware that the recalls, which ballooned to more than 8.5 million vehicles across the globe since October, have damaged its reputation as Toyota executives gave assurance that they are prioritising customers' welfare.

Toyota has been widely scored for its sluggish response to manufacturing lapses and even incurred fines of up to $US16.4 million or $A19.54 million in the United States for its slow reaction when the recall problem started.

Advanced Research Japan Co analyst Koji Endo said that car makers usually upgrade parts and technology when vehicles are remodelled, which should answer some questions on the issue though he admitted that Toyota was hit hard by the recall, underscoring the company's neglect of quality during its accelerated growth periods.

Mr Endo said that with product demands on record high, the tendency to sacrifice quality became eminent and Toyota is facing the consequences at this time with its Lexus line expected to drop in popularity in the US and most likely giving away chunks of its market share to competitors like BMW and Mercedes-Benz.

Toyota furnished the following list as the affected Lexus models: GS350, GS450h, GS460, IS350, LS460, LS600h, LS600hL and Crown models. The company added that the repair would involve about 138,000 vehicles in the US, nearly 92,000 in Japan, 15,000 in Europe, 10,000 in the Middle East, 6,000 in China, 4,000 in Canada, and 8,000 elsewhere.

The company said that so far no accidents have been reported related to the detected flaws though it admitted that up to 200 complaints have been received so far, which came on the heels of additional 17,000 units of Lexus hybrids recalled last week to rectify possible fuel can spills in the event of a rear-end crash.