Swedish boutique supercar maker Koenigsegg Group AB has reached an agreement to acquire General Motors Corp.'s (GMGMQ) Saab Automobile AB unit for an undisclosed sum, the companies said Tuesday.

"Closing this deal represents the best chance for Saab to emerge a stronger company," said GM Europe President Carl-Peter Forster.

The sale, expected to close by the end of the third quarter of this year, includes an expected $600 million funding commitment from the European Investment Bank guaranteed by the Swedish government, the companies said in a statement.

"Today's announcement is great news for Saab's current and future customers, dealers, suppliers and employees around the globe," said Jan Ake Jonsson, managing director of Saab.

As part of the proposed transaction, GM will continue to provide Saab with design and powertrain technology during a defined time period.

Saab, part of GM since 2000, was granted bankruptcy protection in Sweden Feb. 20 after GM said it wanted to offload the unit by the year's end.

GM has been trying for months to find a buyer for Saab, and people familiar with the situation said last week that a deal with Koenigsegg could be reached soon.

The Swedish government said Thursday it had authorized its National Debt Office to start formal discussions about the state guaranteeing a EUR500 million ($700 million) loan that Saab has sought from the European Investment Bank.

GM itself filed for protection from its creditors earlier this month.

Last year, Saab sold a little less than 94,000 cars. It employs about 3,400 workers, most at its main factory in Trollhattan in southwestern Sweden.

Company Web site: www.saab.com

-By Ian Edmondson, Dow Jones Newswires; +46-8-5451-3094; ian.edmondson@dowjones.com