A supervisory board member representing Adam Opel GmbH's workforce Thursday spoke out against Fiat SpA's (F.MI) interest in a possible stake in the German car maker.

Opel ran into liquidity troubles after its U.S. parent company General Motors Corp. (GM) struggled to live up to payment obligations and issued promissory notes to its subsidiary.

Despite the apparent difficulties at Opel, the IG Metall labor union isn't of the opinion that a significant Fiat stake could help Opel, said Opel supervisory board member Armin Schild, who is also the head of the union's Frankfurt section.

"Even the strongest child can't bear two sick parents," said Schild. Fiat would put Opel's future on the line again, he added, "because Fiat is sitting on dramatic overcapacity."

Labor Union Web site: www.igmetall.de

-By Roman Kessler, Dow Jones Newswires, +4969 2972 5514, roman.kessler@dowjones.com