Toyoda's article comes two days before he is due to give testimony before a US congressional hearing into his company's handling of the recall and its response to safety concerns.

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Al Jazeera's John Terret reports on Toyota's mounting problems

It also appeared on the same day that the car manufacturer was presented with a subpoena from a US federal grand jury ordering it to handover documents related to the recalls.

Depending on the evidence the grand jury probe reveals, the case could lead to eventual criminal charges being brought against Toyota.

Toyota's US headquarters said on Monday that it would co-operate fully with the inquiry but gave no further details.

As well as two congressional investigations, Toyota is facing a host of US class-action lawsuits potentially costing billions of dollars that link defects in its vehicles to more than 30 deaths.

'Back to basics'

Writing in Tuesday's Wall Street Journal a contrite Toyoda said: "I recognise that we must do better - much better - in responding to safety issues."

"It is clear to me that in recent years we didn't listen as carefully as we should - or respond as quickly as we must - to our customers' concerns"

Akio Toyoda,
Toyota president

He said: "It is clear to me that in recent years we didn't listen as carefully as we should - or respond as quickly as we must - to our customers' concerns".

Toyoda, who is the grandson of the carmaker's founder, said he would take the company "back to basics", pledging that "Toyota will set a new standard for transparency and speed of response on safety issues".

He is due to begin testimony before the congressional inquiry on Wednesday

Critics, including some members of the US congress, have attacked Toyota's response to complaints of sudden, unintended acceleration, accusing it of trying to cover up defects, which also extend to the brake systems of its flagship Prius hybrid cars.

'Evidence hidden'

News of the US grand jury investigation came hours after the release of a document apparently showing Toyota knew of accelerator safety problems in its vehicles as early as 2007.

The internal memo appears to show Toyota executives gloating over their success in limiting a 2007 recall on some cars where the driver's foot mat interfered with the accelerator.

The memo is among thousands that a congressional committee has requested in a subpoena of Dimitrios Biller, who worked as a US lawyer for Toyota from 2003 to 2007.

Biller, who is now in a legal dispute with Toyota, said the internal company documents show the firm was hiding evidence of safety defects from consumers and regulators.