DETROIT — General Motors said Monday that it had decided to sever its ties with the Swedish automaker Saab and its commitment to supply it with vehicle components and the 9-4X model because of the risks posed by Saab’s pending sale to Chinese companies.

“Although General Motors is open to the continued supply of powertrains and other components to Saab under appropriate terms and conditions, G.M. will not agree to the continuation of the existing technology licenses or the continued supply of 9-4X vehicles to Saab following the proposed change in ownership as it would not be in the best interests of G.M. shareholders,” said Jim Cain, a G.M. spokesman.

The statement represented a hardening in G.M.’s opposition to the proposed rescue plan for Saab and appeared to lengthen the odds for the brand’s survival. On Friday, G.M. said that it would be difficult to support a sale of Saab if it hurt G.M.’s competitive position in China and other key markets, reported The New York Times.

Swedish Automobile, the struggling company that owns Saab, said it would discuss General Motor’s objections with the company.

“I expect this to happen tomorrow. There are always alternatives but we only have limited time,” the chief executive of Swedish Automobile, Victor R. Muller, told Reuters in a text message.

Pang Da Automobile Trade and Zhejiang Youngman Lotus Automobile have struck a deal to buy Saab from Swedish Automobile, in what amounts to a rescue plan for Saab, which was formerly owned by G.M. The sale, however, awaits approval from G.M., which has preferred shares in Saab and has supplied it with crucial components. In addition, the Saab 9-4X, a crossover vehicle, is based on G.M.’s Cadillac SRX and is built at a G.M. plant in Mexico.

Separately, G.M. said that D.Nick Reilly, the head of its European business, would retire after 37 years with the company and be succeeded by Karl-Friedrich Stracke, chief executive of Opel/Vauxhall.

Mr. Stracke will keep his current title after he takes over as president of GM Europe on Jan. 1, G.M. said. GM Europe comprises Opel, Vauxhall, Cadillac Europe and Chevrolet Europe.