Washington  - US automotive giants General Motors Corp and Chrysler LLC scaled up their restructuring efforts Tuesday in a bid to hold onto 17.4 billion dollars in emergency government loans and avoid declaring bankruptcy.

But the two US industrial icons said they would need nearly 10 billion dollars in additional federal aid over the coming months to weather the ongoing US recession and the worst industrywide downturn in a quarter-century. GM said it could need as much as 16.6 billion dollars by 2011 if the economy continues deteriorating.

Faced with a government deadline to submit proof that they can survive the economic crisis, GM and Chrysler offered their latest detailed proposals to slash labour costs, close manufacturing plants and dealerships and focus more on their core brands.

The White House said it would review the plans over the coming days. The two carmakers are required to prove by March 31 that they can survive or be forced to repay the federal loans - a move that would almost certainly force them into bankruptcy.

GM's plan involves cutting 47,000 jobs worldwide over the next year, including 26,000 outside the United States, and shuttering another five plants. The company will sell or phase out at least three of its brands: Hummer, Saturn and Saab. German subsidiary Opel could also be on the chopping block.

The restructuring efforts could make the company profitable in two years and were "significantly more aggressive" than a plan outlined in December, due to an even sharper deterioration of the US car demand in the last month, chief executive Rick Wagoner said.

Chrysler outlined a plan to slash 3,000 more jobs and cut 700 million dollars in fixed costs this year, on top of 3.1 billion dollars cut in 2008. The company has already slashed more than 32,000 jobs since a restructuring effort began in 2007.

Chrysler is also seeking an alliance with Italian carmaker Fiat SPA, which chief executive Robert Nardelli said could "enhance" its viability by sharing technology and introducing smaller cars to the US market.

But Nardelli said he was convinced Chrysler could survive as a "standalone" firm even if the Fiat talks fail. Many analysts regard Chrysler as the carmaker least likely to survive the economic crisis on its own. GM and Chrysler have also held merger talks in the past.

GM and Chrysler said they had reached agreements with their chief labour union, the United Auto Workers, to further cut wages. Few details were released as the deals have not been approved by UAW membership.

The two carmakers have been locked for weeks in negotiations with creditors and labour unions, hoping to gain billions of dollars in concessions on wage, retirement and health costs.

GM was given 13.4 billion dollars and Chrysler 4 billion dollars in emergency government loans in December by former president George W Bush.

Since then, the US and global downturn has only worsened. GM's car sales fell 49 per cent in January compared to a year earlier and Chrysler's dropped 55 per cent. US car sales overall fell more than 35 per cent on the month.

GM said it needed at least another 4.6 billion dollars in the short term to survive. Another 4.5 billion dollars would be necessary by 2011, but that could rise to 12 billion dollars if the sales climate deteriorates even further.

GM is also in talks with governments in Germany, Canada, Sweden, Britain and Thailand for additional money. Saab could file for bankruptcy this month if it doesn't get help from Sweden, GM said.

Chrysler said it would need another 5 billion dollars to survive an "unprecedented decline" in US car sales.

Ford Motor Co was the only one of the Detroit-based "Big Three" firms that did not seek urgent government help in December, but has still been going through its own restructuring moves to weather the crisis.

The federal money came with strict conditions: both companies have until March 31 to make demonstrable progress in carrying out their restructuring plans as laid out in Tuesday's reports.

If they cannot prove to a presidential task force that they have made the changes to survive, GM and Chrysler will have to pay back the borrowed money to the government and will get no more federal loans, according to the original terms of the agreement.

"It is clear that going forward, more will be required from everyone involved - creditors, suppliers, dealers, labour and auto executives themselves - to ensure the viability of these companies going forward," White House press secretary Robert Gibbs said.

President Barack Obama has said that the carmakers' survival is critical to the economy, but many in Congress have argued that bankruptcy reorganization may be the best and only option for an industry that has for decades failed to adapt to global demand for smaller, greener cars.

GM's share price closed down 12.8 per cent Tuesday at 2.18 dollars, ahead of the evening restructuring announcement. Chrysler shares are not traded since its 2007 purchase by private-equity firm Cerberus Capital Management from Germany's Daimler AG, which still owns 20 per cent of the US carmaker.

Both GM and Chrysler warned that bankruptcy protection should be an absolute last resort and could end up costing taxpayers billions of dollars more. GM Vice President Fritz Henderson said that sales would "fall off a cliff" if the company took that step. (dpa)