Mumbai: General Motors Corp, the No 1 US auto maker, said it could take a $1 billion charge in the second quarter by restating accounts related to its bankrupt auto parts business Delphi Corporation.

The US Securities and Exchange Commission has asked GM to show documents related to the accounting used in its latest annual report, GM spokeswoman Renee Rashid-Merem said.

GM said the regulators are reviewing its accounting for commodity and foreign-exchange contracts.

In an SEC filing, GM said its exposure to bankrupt auto parts maker Delphi Corp. was probably $7 billion while it had accounted for $6 billion.

"We have taken a $6 billion charge to date," Rashid-Merem said. "In order to hit that $7 billion, we would potentially take an additional $1 billion charge in the second quarter."

GM said it may also have to restate some results after the SEC reviews accounting at the former General Motors Acceptance Corp. finance unit.

The automaker earlier this month estimated an initial payment of $400 million and a range of $100 million to $200 million a year as part of a bailout of Delphi. GM spun off the parts-making unit in 1999.

Retirement costs of some former GM workers at Delphi may total $7 billion, up from an earlier estimated range of $6 billion to $7.5 billion, GM said in the filing.

The SEC request extends GM''s two-year struggle to clean up its accounting and end restatements. Last year, the carmaker restated results dating back to 2000 and reorganised its accounting office by combining the jobs of controller and chief accounting officer.

GM in March delayed its 2006 annual report to restate results from 2002 to 2005. The SEC inquiry relates to the accounting in that report.