General Motors has said US regulators are reviewing the automaker's accounting for commodity and foreign-exchange contracts and raised its estimate of costs to bail out parts subsidiary Delphi.

According to Bloomberg News, GM said in a regulatory filing today the US Securities and Exchange Commission is seeking documents related to the accounting used in its latest annual report. Separately, GM said it may also have to restate some results after the SEC reviews accounting at the former General Motors Acceptance Corp. finance unit.

Bloomberg noted that the SEC request extends GM's two-year struggle to clean up its accounting and end restatements. Last year, the car maker 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, the news agency said.

According to Bloomberg News, GM also said it expects costs related to the bailout of Delphi to be modified by the withdrawal of private-equity firm Cerberus Capital Management as the lead party in a $US3.4bn investment.

As part of those changes, GM now expects to pay $500 million when Troy, Michigan-based Delphi emerges from bankruptcy and provide annual labour-related payments of between $300m and $400m along with additional yearly payments of $100m, the report said.