In a further sign of problems at Saab, the Swedish auto maker has been forced to halt production on Tuesday due to a shortage of components. The brief shutdown raises questions about the company’s ability to meet its production schedule. It comes just days after Saab’s long-serving chief executive announced his decision to retire and parent company Spyker Cars NV reported a steep loss for 2010 and said it would raise €13.6 million ($19.2 million) in a capital increase.

On Monday, Spyker Chief Executive Victor Muller met with officials at Sweden’s National Debt Office to provide assurances over collateral to meet the terms of the credit guarantees the government provided to secure European Investment Bank funding that helped it to buy Saab last year. Spyker’s investors have been unnerved by the latest developments. The company’s shares were down 8.8% at €3.90 by late morning in Europe, partially retracing a drop of as much as 20%. The stock has shed more than one-fifth of its value since Thursday, the day before the Dutch car maker announced its earnings.

Production at Saab’s Trollhattan factory, which makes 224 cars a day, was halted briefly Tuesday. Spyker confirmed that some suppliers had halted supplies to Saab due to talks about payments and terms, but Saab production had restarted. In a statement, the Dutch company said it had sufficient funds to meet its immediate needs and was seeking to strengthen its financial position and capital structure.

That Saab is lagging with its payments also was confirmed by FKG, a trade association representing Scandinavian auto industry suppliers. Saab’s advertising agency Lowe Brindfors has cancelled all of its ongoing work for Saab because of unpaid bills, Swedish media business paper Resume reported.

Spyker Cars bought unprofitable Saab in February 2010 from General Motors Co., which at the time was wrestling with its own financial problems that resulted in the U.S. auto maker seeking protection from its creditors. Spyker pledged it would make Saab profitable again by 2012. The company paid GM $74 million in cash for Saab, and secured several loans to fund its business plan, including one for €400 million from the EIB. The Swedish government provided loan guarantees.

Spyker expected to sell 50,000 Saab cars in 2010, but this target was lowered during the course of the year to 30,000 to 35,000 cars. It sold 31,696 cars last year. Spyker said it still expects to sell 80,000 cars in 2011 and 120,000 cars in 2012, which should allow the car maker to turn a profit. The company booked a €218 million net loss in 2010.