Washington - General Motors Corp's auditors said there was "substantial doubt" that the iconic US carmaker can survive a massive downturn in the industry, according to an annual report filed Thursday with US regulators.

Despite receiving 13.4 billion dollars in emergency government loans since December, GM said it may have to seek bankruptcy protection if it cannot complete a major restructuring effort, in the filing with the Securities and Exchange Commission.

GM suffered a 52-per-cent drop in US car sales in February and has lost its status as the world's largest carmaker to Japan's Toyota Motor Corp.

The company has said it will cut as many as 47,000 jobs worldwide and is in the middle of tough negotiations with labour unions to reduce salaries.

Accounting firm Deloitte & Touche, which performed the audit, said GM's "recurring losses from operations, stockholders deficit, and inability to generate sufficient cash flow to meet its obligations and sustain its operations raise substantial doubt about its ability to continue as a going concern."

GM has until March 31 to prove it can avoid bankruptcy or risk losing the government loans.

The carmaker said its survival depended on many factors out of its control, including "substantially higher" demand for its cars. But GM said there was "no assurance" that sales will recover in the near future.