General Motors Corp has attracted 20 potential buyers for its struggling Saab brand and could complete a sale by June as it rushes to offload unprofitable units in a sweeping restructuring.

In the United States, GM rival Ford Motor Co said voluntary efforts had helped it slash automotive debt by $9.9 billion, or about 38 percent, sending the automaker's shares up as much as 23 percent before closing 16 percent higher.

A spokesman for Germany's economic minister said the government was in talks with several potential investors over GM's Opel unit as the U.S. automaker, facing the threat of bankruptcy, scrambled to restructure by divesting money-losing operations and winning concessions from creditors.

Underscoring the depth of the downturn that has hit every global automaker, British new car sales fell more than 30 percent in March and German car maker Audi said it sold 11 percent fewer cars in March than a year earlier.

Britain's dismal sales prompted renewed calls for a government incentive program to encourage owners to turn in older vehicles like one that has supported German sales recently.

The fate of GM and its units remained paramount, with the U.S. government having ordered the nation's largest automaker to cut deeper and faster if it wants to continue to receive emergency support.

GM, which is operating under $13.4 billion of emergency U.S. government loans, has planned to sever ties with Saab by the start of next year as well as divest other units. Saab sought protection from creditors in February to survive the downturn and buy time to find a new owner.

SAAB SEEKS CREDITOR CONCESSIONS

Saab is planning to ask creditors to write off about 75 percent of its debt as part of a deal to return to positive cash flow by 2011, according to a turnaround plan presented to creditors on Monday.

Saab's administrator said about 20 potential buyers are looking at the company and that a deal is expected to be completed in June.

Saab needs $1 billion of financing to help it overhaul production and launch new car models. It aims to raise $600 million of that sum from the European Investment Bank while GM would inject $400 million in the shape of debt write-offs and production equipment, the court filing showed.

In Germany, a spokesman for the economy minister said the government was talking to several partners over GM unit Opel, but would not comment on a reported interest from Abu Dhabi or other details.

A labor leader at Opel said earlier on Monday that the German state of North Rhine-Westfalia where Opel has a plant had held talks with Abu Dhabi for a possible investment in Opel and he was not opposed to such a development.

Opel has said it needs 3.3 billion euros ($4.47 billion) in state aid to avert layoffs and plant closures. It is under pressure to win private-sector support as a precondition for state loan guarantees.

So far, there have been no serious public declarations of interest in an investment in Opel, fanning speculation over who may throw their hat in the ring.

On Monday, BMW joined a growing list of carmakers -- including Daimler and PSA Peugeot-Citroen
-- that have said they were not considering a move on the GM unit.

Shares and bond prices on GM rose after the reports that the Saab brand had attracted interest from 20 potential buyers. GM stock reached $2.33 before closing at $2.27, up 8 percent on the day. GM's 8.375 percent bond due 2033 rose 1.22 cents to 12.75 cents, according to MarketAxess.

FORD TURNAROUND LEADS U.S. RIVALS

Ford said its debt restructuring efforts would slash annual interest expenses by more than $500 million. The restructuring was part of the automaker's overall plan to make cuts that would balance those being sought by rivals GM and Chrysler.

The automaker previously had obtained concessions from the United Auto Workers union on labor costs and the cash funding of a healthcare trust for union retirees. Both were contingent on substantial cuts in Ford's debt structure over time.

Ford, the only U.S. automaker not operating with emergency U.S. government aid, has said it has sufficient liquidity to make it through 2009 without seeking bridge loans as long as conditions do not worsen substantially.

Although Ford's future still depends on a recovery in auto sales, the debt restructuring and union contract changes have decreased the chances of a Ford bankruptcy, said Shelly Lombard, a bond analyst at Gimme Credit.

Ford shares rose to as high as $3.99 on Monday after the restructuring results were announced. Ford's 6.625 percent bond due 2028 rose 2.5 cents to 31 cents on the dollar on Monday, according to MarketAxess.

At the end of March, the U.S. government rejected the turnaround plans of GM and Chrysler, giving GM 60 days to rework its strategy and Chrysler a month to make a proposed merger with Italy's Fiat SpA a reality.

Chrysler, about 80 percent controlled by Cerberus Capital Management , on Monday named U.S.-based A123 Systems as battery supplier for its first electric vehicles planned to debut in showrooms next year.

(Reporting by Soyoung Kim, Poornima Gupta, David Bailey, Madeline Chambers, Karen Brettell, Kerstin Gehmlich, Eva Kuehnen, Matt Falloon, Christina Fincher, Stefano Ambrogi, Sven Nordenstam and Johannes Hellstrom, Niklas Pollard; Writing by Richard Hubbard and David Bailey; Editing by Andrew Macdonald and Matthew Lewis)

($1=.6702 Pound)